During + noun phrase
During is a preposition. It is followed by a noun, not a clause. It means "at some point within a period" — it tells us when something happened, not how long.
| Example | Note |
|---|---|
| She fell asleep during the film. | at some point while the film was on |
| He worked as a waiter during the summer. | at some point in that summer |
| There was a power cut during the night. | at some point during the night |
For + duration
For answers "how long?" It is followed by a quantity of time. It tells us the length of a period.
| Example | Note |
|---|---|
| I studied for three hours. | duration of studying |
| She's been working here for five years. | with perfect tenses (from past to now) |
| We waited for a long time. | indefinite duration |
for vs since:
Use for + duration: "for three years" / "for a week". Use since + point in time: "since 2020" / "since Monday". Both go with perfect tenses.
While + clause
While is a conjunction. It is followed by a subject + verb. It shows that two actions were happening at the same time.
| Example | Note |
|---|---|
| The phone rang while I was cooking. | two simultaneous actions (past continuous typical) |
| While she was sleeping, he left. | time clause first — use comma |
| I listen to music while I work. | present — habitual simultaneous actions |
Compare during / for / while
| Word | Followed by | Answers |
|---|---|---|
| during | noun / noun phrase | "when?" (within a period) |
| for | quantity of time (three hours, a week) | "how long?" |
| while | subject + verb (full clause) | "at the same time as" (what else was happening) |
"She read during the flight." (when — within the flight)
"She read for two hours." (how long)
"She read while the baby slept." (simultaneously)
"She read for two hours." (how long)
"She read while the baby slept." (simultaneously)
Exercises
Choose the correct word.
1. I fell asleep ___ the lecture.
2. She lived in Paris ___ six months.
3. I saw an accident ___ I was driving to work.
4. The company grew a lot ___ the economic boom.
5. We've been friends ___ over twenty years.