22. For, since, during, yet, etc.

For is used for general periods of time - 2 hours, three days, one month. Since is used for a specific time - 1998, January, last week, one month ago.

for	since
a period of time	a point in past time
	x------------
20 minutes	6.15pm
three days	Monday
6 months	January
4 years	1994
2 centuries	1800
a long time	I left school
ever	the beginning of time

• We use since to indicate a starting point:

e.g. They haven’t met since the wedding.

• We can use It’s a long time, two weeks, etc.+ since + Past Simple to focus on the period:

e.g.It’s ages since I saw Eva.

• We use for to say how long something lasts:

e.g. I haven’t seen Eva for ages.

Over/during

We use over/during to indicate the period of time in which something happens or develops:

Over/during the last eighteen months there have been three tax increases.

10. From … to/until/till

• We use from … to/until/till to indicate when something starts and ends – from one point in time to another:

e.g. Dinner is from eight o’clock to ten o’clock.

• We can use from…without to/until/till if we do not say when something ends:

e.g. I was training from ten o’clock.

For and during

• For answers the question “how long”? We use it with time expressions to talk about actions that last the whole of the period of time:

He was with the company for forty years.

1958 1998

His time with the company now

0. We use during + that week, your stay, the match, etc. when one action happened inside a period of time:

e.g. During that year he rose from deputy manager to managing director.

• Here are some typical phrases we use with for and during:

For two hours/ a whole week/a long time/a couple of days/a minute or so

During office hours/the day/the full ninety nineties/the twentieth century/the interval

During or while?

During is a preposition. We use it before a noun (phrase). We never use during with clause.

While is a conjunction. We use it with a clause:

e.g. We didn’t see anybody during the holidays. (noun)

We didn’t see anybody while we were on holiday. (clause)

Already, yet
We use already to say that something happened sooner than expected.	I am sorry, she has already gone home. The film has already started. She's only four years old and she can already read.
Already usually comes before the main verb or between an auxiliary or modal verb and the main verb.
We use yet in questions or negative statements to talk about things that we expected to happen before now.	Have you finished the work yet? I haven't seen the new James Bond film yet. A: Have you met our new colleague? B: Not yet.
Yet usually comes at the end of the sentence.