The correct answers are when and after.
Use when to introduce a specific event in the past simple that interrupts an ongoing background action in the past continuous ("were feeding... when the alarm went off").
Use after to show that an action (running away) logically followed a previous completed event (the vault being breached).
Adverb
An adverb is a word that modifies a verb, adjective, determiner, clause, preposition, or sentence. Adverbs typically express manner, place, time, frequency, degree, level of certainty, etc., answering questions such as how?, in what way?, when?, where?, and to what extent?. This function is called the adverbial function, and may be realized by single words (adverbs) or by multi-word expressions (adverbial phrases and adverbial clauses).
Adverbs are traditionally regarded as one of the parts of speech. However, modern linguists note that the term "adverb" has come to be used as a kind of "catch-all" category, used to classify words with various different types of syntactic behavior, not necessarily having much in common except that they do not fit into any of the other available categories (noun, adjective, preposition, etc.)
Simple Past
The simple past, past simple or past indefinite, sometimes called the preterite, is the basic form of the past tense in Modern English. It is used principally to describe events in the past, although it also has some other uses. Regular English verbs form the simple past in -ed; however there are a few hundred irregular verbs with different forms.
The term "simple" is used to distinguish the syntactical construction whose basic form uses the plain past tense alone, from other past tense constructions which use auxiliaries in combination with participles, such as the past perfect and past progressive.
Formation
Regular verbs form the simple past end*-ed*; however there are a few hundred irregular verbs with different forms. For details see.
Most verbs have a single form of the simple past, independent of the person or number of the subject (there is no addition of -s for the third person singular as in the simple present).
However, the copula verb be has two past tense forms: was for the first and third persons singular, and were in other instances.
The form were can also be used in place of was in conditional clauses and the like; for information on this, see subjunctive.
This is the only case in modern English where a distinction in form is made between the indicative and subjunctive moods in the past tense.
Questions, other clauses requiring inversion, negations with not, and emphatic forms of the simple past use the auxiliary did.
A full list of forms is given below, using the (regular) verb help as an example:
- Basic simple past:
- I/you/he/she/it/we/they helped
- Expanded (emphatic) simple past:
- I/you/he/she/it/we/they did help
- Question form:
- Did I/you/he/she/it/we/they help?
- Negative:
- I/you/he/she/it/we/they did not (didn't) help
- Negative question:
- Did I/you/he/she/it/we/they not help? / Didn't I/you/he/she/it/we/they help?
Usage
The simple past is used for a single event (or sequence of such events) in the past, and also for past habitual action:
- He took the money and ran.
- I visited them every day for a year.
It can also refer to a past state:
- I knew how to fight even as a child.
For action that was ongoing at the time referred to, the past progressive is generally used instead (e.g. I was cooking). The same can apply to states, if temporary (e.g. the ball was lying on the sidewalk), but some stative verbs do not generally use the progressive aspect at all, and in these cases the simple past is used even for a temporary state:
- The dog was in its kennel.
However, with verbs of sensing, it is common in such circumstances to use could see in place of saw, could hear in place of heard, etc.
- I felt cold.
If one action interrupts another, then it is usual for the interrupted (ongoing) action to be expressed with the past progressive, and the action that interrupted it to be in the simple past:
- Your mother called while you were cooking.
The simple past is often close in meaning to the present perfect.
The simple past is used when the event happened at a particular time in the past, or during a period which ended in the past (i.e. a period that does not last up until the present time).
This time frame may be explicitly stated, or implicit in the context (for example the past tense is often used when describing a sequence of past events).
- I was born in 1980.
- We turned the oven off two minutes ago.
- I came home at 6 o'clock.
- When did they get married?
- We wrote two letters this morning.
- She placed the letter on the table, sighed, and left the house.Contrast these examples with those given at.
Note also that for past actions that occurred before the relevant past time frame, the past perfect is used.
Various compound constructions exist for denoting past habitual action.
The sentence When I was young, I played football every Saturday might alternatively be phrased using used to (... I used to play ...) or using would (... I would play...).
The simple past also has some uses in which it does not refer to a past time.
- If he walked faster, he would get home earlier.
- I wish I knew what his name was.
These are generally in condition clauses and some other dependent clauses referring to hypothetical circumstances, as well as certain expressions of wish:
- He said he wanted to go on the slide.
Past Progressive
The past progressive or past continuous construction combines progressive aspect with past tense, and is formed using the past tense of be (was or were) with the present participle of the main verb.
It indicates an action that was ongoing at the past time being considered:
- At three o'clock yesterday, I was working in the garden. For stative verbs that do not use the progressive aspect, the simple past is used instead (At three o'clock yesterday we were in the garden).
The past progressive is often used to denote an action that was interrupted by an event, or for two actions taking place in parallel:
- While I was washing the dishes, I heard a loud noise.
- While you were washing the dishes, Sue was walking the dog.(Interrupted actions in the past can also sometimes be denoted using the past perfect progressive.)
The past progressive can also be used to refer to past action that occurred over a range of time and is viewed as an ongoing situation:
- I was working in the garden all day yesterday. That could also be expressed using the simple past, as I worked..., which implies that the action is viewed as a unitary event (although the effective meaning is not very different).
Past Perfect
The past perfect, sometimes called the pluperfect, combines past tense with perfect aspect; it is formed by combining had (the past tense of the auxiliary have) with the past participle of the main verb.
It is used when referring to an event that took place prior to the time frame being considered.
This time frame may be stated explicitly, as a stated time or the time of another past action:
- We had finished the job by 2 o'clock.
- He had already left when we arrived.
The time frame may also be understood implicitly from the previous or later context:
- I was eating ... I had invited Jim to the meal but he was unable to attend. (i.e. I invited him before I started eating)
- I had lost my way. (i.e. this happened prior to the time of the past events I am describing or am about to describe)
Compare He had left when we arrived (where his leaving preceded our arrival), with the form with the simple past, He left when we arrived (where his leaving was concurrent with or shortly after our arrival).
Note that unlike the present perfect, the past perfect can readily be used with an adverb specifying a past time frame for the occurrence.
For example, while it is incorrect to say I have done it last Friday (the use of last Friday, specifying the past time, would require the simple past rather than the present perfect), there is no such objection to a sentence like "I had done it the previous Friday".
The past perfect can also be used for states or repeated occurrences pertaining over a period up to a time in the past, particularly in stating "for how long" or since when". However, if the state is temporary and the verb can be used in the progressive aspect, the past perfect progressive would normally be used instead. Some examples with the plain past perfect:
- I had lived in that house for 10 years.
- The children had been in their room since lunchtime.
Past Perfect Progressive
The past perfect progressive or past perfect continuous (also known as the pluperfect progressive or pluperfect continuous) combines perfect progressive aspect with past tense.
It is formed by combining had (the past tense of auxiliary have), been (the past participle of be), and the present participle of the main verb.
Uses of the past perfect progressive are analogous to those of the present perfect progressive, except that the point of reference is in the past.
For example:
- I was tired because I had been running.
- By yesterday morning they had already been working for twelve hours.
- Among the witnesses was John Smith, who had been staying at the hotel since July 10.
This form is sometimes used for actions in the past that were interrupted by some event (compare the use of the past progressive as given above).
For example:
- I had been working on my novel when she entered the room to talk to me.
This implies that I stopped working when she came in (or had already stopped a short time before); the plain past progressive (I was working...) would not necessarily carry this implication.
If the verb in question does not use the progressive aspect, then the plain past perfect is used instead.
The past perfect progressive may also have additional specific uses similar to those of the plain past perfect.
Conjunction
In grammar, a conjunction is a part of speech that connects words, phrases, or clauses that are called the conjuncts of the conjoining construction. The term discourse marker is mostly used for conjunctions joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" must be defined for each language. In English a given word may have several senses, being either a preposition or a conjunction depending on the syntax of the sentence (for example, "after" being a preposition in "he left after the fight" versus it being a conjunction in "he left after they fought"). In general, a conjunction is an invariable grammatical particle and it may or may not stand between the items conjoined.
The definition may also be extended to idiomatic phrases that behave as a unit with the same function, e.g. "as well as", "provided that".
A simple literary example of a conjunction: "the truth of nature, and the power of giving interest". (Samuel Taylor Coleridge's Biographia Literaria)
Conjunctions may be placed at the beginning of sentences: "But some superstition about the practice persists".
Examples
- "But she must give security that she will not marry without royal consent, if she holds her lands of the Crown, or without the consent of whatever other lord she may hold them of."—Magna Carta (1215), translated into modern English
- "But we, or our chief justice if we are not in England, are first to be informed."— Magna Carta (1215), translated into modern English
- "And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes and our sacred Honor."
- "But in all such Cases the Votes of both Houses shall be determined by Yeas and Nays, and the Names of the Persons voting for and against the Bill shall be entered on the Journal of each House respectively."—United States Constitution (1787)
- "And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof."—United States Constitution (1787)
- "And this power has been exercised when the last act, required from the person possessing the power, has been performed."—United States Supreme Court Judgment (1803)
- "But, in a larger sense, we can not dedicate, we can not consecrate, we can not hallow this ground." Abraham Lincoln's Gettysburg Address (1863)
- "Yet, if God wills that it continue until all the wealth piled by the bondsman's two hundred and fifty years of unrequited toil shall be sunk, and until every drop of blood drawn with the lash shall be paid by another drawn with the sword, as was said three thousand years ago, so still it must be said "the judgments of the Lord are true and righteous altogether."Abraham Lincoln's Second Inaugural Address (1865)
- "So the inquiries can coexist, though there is much overlap between them."
- "And it appears that it was this latter factor which underlay the dismissal of the appeal by the majority. But it seems to me that the question of whether it is fair, just and reasonable is better considered against the background of whether a sufficiently proximate relationship exists."
- "But the earlier decisions in Pratap Narain Singh Deo and Valsala K. were not brought to the notice of the Court in the two later decisions in Mubasir Ahmed and Mohd. Nasir."
- "And now we have Facebook and Twitter and Wordpress and Tumblr and all those other platforms that take our daily doings and transform them into media."
- "So any modern editor who is not paranoid is a fool".
- "And strikes are protected globally, existing in many of the countries with labour laws outside the Wagner Act model."
Clause
A clause is a grammatical unit built around a verb that typically contains a subject and a predicate. Understanding clauses is essential because they are the core building blocks of every sentence you read, write, or speak.
What makes a clause?
At minimum, a clause needs a verb (the predicate) and, in most cases, a subject — the person or thing the verb says something about. The predicate can also include objects, complements, and modifiers.
- She laughed. — subject (she) + verb (laughed)
- The manager approved the budget yesterday. — subject + verb + object + modifier
Sometimes the subject is left out. This happens regularly in imperative sentences and non-finite clauses:
- Sit down. — no visible subject, but "you" is understood
- Walking home, I noticed the shop was closed. — the -ing clause has no stated subject
Types of clauses
There are two main types:
-
Independent clause (also called a main clause) — can stand on its own as a complete sentence. It contains a finite verb.
- I missed the bus.
-
Dependent clause (also called a subordinate clause) — cannot stand alone and needs an independent clause to make sense.
- Because I overslept — incomplete on its own
Combine them and you get a complex sentence:
- I missed the bus because I overslept.
A simple sentence has one independent clause. More complex sentences combine independent and dependent clauses in various ways.
Quick check: If you can remove a group of words from a sentence and it still has a subject + finite verb and makes sense on its own, that group is likely an independent clause.
Why clauses matter
Recognizing clause boundaries helps you punctuate correctly, avoid run-on sentences, and build more varied, natural-sounding writing. Once you can spot where one clause ends and another begins, sentence structure becomes much easier to manage.
Ready to practice? Try Complex Sentence for the basics, then move on to Complex Sentence: Adverbials or Participle Clauses: Shortening Sentences with -ing and Having + Past Participle to deepen your skills.
B2 | Upper Intermediate
B2, or Upper Intermediate, is the fourth level on the CEFR scale. It marks the point where you move from "getting by" to genuinely comfortable communication — handling complex topics, expressing nuanced opinions, and understanding most of what you read or hear in real-world contexts.
What a B2 user can do
At this level, you're expected to:
- Understand complex texts on both concrete and abstract topics, including technical discussions in your own field.
- Follow extended speech and lectures, even when the structure isn't entirely clear, as long as the topic is reasonably familiar.
- Interact fluently and spontaneously enough that conversations with native speakers flow naturally — without strain on either side.
- Produce clear, detailed text on a wide range of subjects, using connectors and cohesive devices to build well-structured arguments.
- Explain and defend a viewpoint on a topical issue, weighing the advantages and disadvantages of different options.
- Recognize implicit meaning — reading between the lines in demanding, longer texts.
What B2 grammar looks like in practice
B2 is where grammar stops being about isolated rules and starts being about flexibility and precision. You're expected to control structures like:
- Advanced conditionals and mixed conditionals — moving beyond simple if-clauses to express hypothetical and counterfactual meaning.
- Passive voice in varied tenses and contexts, not just present and past simple.
- Reported speech with correct sequence of tenses, including backshifting and reporting verbs.
- Participle clauses and the distinction between participles and gerunds.
- Comparative and superlative structures beyond basic -er/-est, including double comparatives and qualifying expressions.
Errors still happen at B2, but they rarely cause misunderstanding. The goal is controlled, flexible use of language across social, academic, and professional settings.
How B2 fits in the CEFR progression
B2 builds directly on the foundations of B1 (Intermediate) and prepares you for C1 (Advanced). Many university entrance exams, professional certifications, and immigration requirements target B2 as the minimum standard.
Self-check: If you can read a newspaper editorial, follow most of a TED talk without subtitles, and write a clear essay arguing a position — you're likely operating at B2.
Ready to test yourself? Try Is your English level B2/Upper Intermediate? or practise specific B2 grammar with challenges like Basics. Advanced Conditionals And "wish", Basics. Passive Voice, and Sequence of Tenses in Indirect Speech.
Difficulty: Medium
Medium difficulty. Difficulty levels represent author's opinion about how hard a question or challenge is.