Tense, articles and conditionals are the three systems that decide whether a sentence places events correctly in time and marks them as old or new information. They are also the areas where second-language writers most often rely on feel and get it wrong, because the mother tongue marks these things differently or not at all.
The good news is that all three are closed systems. There are twelve tenses but only a handful of forms, four conditional patterns, and one decision for each article. Learn the patterns and the errors become visible.
Place the verb on two axes at once: time (present, past, future) and aspect (simple, continuous, perfect, perfect continuous).
What the model omits: it does not tell you which tense a particular time word demands, and it leaves out the sequence rule in reported speech, where a past reporting verb pulls later verbs back one step. Treat it as a map of the system, not a substitute for the time words.
The twelve tenses, each with one anchor word. Learn the anchor, then match it.
| Tense | Form | Uses when |
|---|---|---|
| Present simple | works | habits, general truths, timetables |
| Present continuous | is working | now, temporary situations |
| Present perfect | has worked | past linked to now; for, since, already, yet |
| Present perfect cont. | has been working | duration still continuing |
| Past simple | worked | finished past time; yesterday, in 2015 |
| Past continuous | was working | in progress when something else happened |
| Past perfect | had worked | earlier of two past actions; by the time |
| Past perfect cont. | had been working | duration up to a past point |
| Future simple | will work | prediction, decision now |
| Future continuous | will be working | in progress at a future time |
| Future perfect | will have worked | completed before a future point |
| Future perfect cont. | will have been working | duration up to a future point |
The four conditionals. The pattern is fixed, and the mistake is almost always a mismatched pair.
Never put would in the if-clause: “if I would have known” is wrong, and the third conditional gives if I had known. Likewise, the second conditional pairs a past form in the if-clause with would in the main clause, not another past form.
Articles follow sound and information. Use a before a consonant sound and an before a vowel sound, judged by sound, not spelling: a university, a European, an hour, an MBA. Use the for something already mentioned, unique, or specified by a phrase. Use the zero article for plurals and uncountables in a general sense: water, books, honesty.
By the time the inspector arrived, the staff has been working since six in the morning and had not yet completed the audit.
There is one tense fault. After by the time the inspector arrived, the reference point is in the past, so the duration up to that point needs the past perfect continuous: had been working, not has been working. The since six keeps its point in time, which is correct.
The second verb, had not yet completed, is already the past perfect and correctly places completion before the same past reference point. The corrected sentence reads: By the time the inspector arrived, the staff had been working since six in the morning and had not yet completed the audit.
Which is correct: I have visited Karachi in 2015.
Complete the third conditional: If I ____ known, I would have called.
Which article fits: She waited for ____ hour before the interview.
Which is correct: She has been teaching here ____ 2018.
Without looking back: give the form of the third conditional, and state the rule that separates since from for.
The answer is: if plus had plus past participle, then would have plus past participle. Since takes a point in time and for takes a duration, and both use the present perfect when the period continues to the present.
Fill in the blanks from memory:
The past perfect of the verb work is . In the second conditional, the if-clause uses the past simple and the main clause uses . Before a vowel sound we write the article . A finished past time such as yesterday requires the simple, not the present perfect.
Find every error and correct it: Since five years, the team has been working on the project, and when the funding ended they have already published two papers.
The first fault is the preposition. Since needs a point in time, but five years is a duration, so it becomes For five years. The present perfect continuous that follows is correct, because the activity continues to now.
The second fault is in the past clause. When the funding ended sets a finished past reference point, so an action completed before that point needs the past perfect, not the present perfect: they had already published two papers.
The corrected sentence reads: For five years, the team has been working on the project, and when the funding ended they had already published two papers. The pattern is worth naming: a present reference point takes the present perfect, and a past reference point takes the past perfect.
Tenses and conditionals organise what a sentence says; punctuation organises how it is delivered. The next lesson covers the marks that separate clauses and lists, and the two boundary errors — the comma splice and the run-on — that turn two sentences into one illegal one.