Prepositions of Time and Date:

I. at, on

at a time: at dawn, at six, at midnight, at 4:50

at an age: at sixteen/at the age of sixteen   She got married at seventeen.

on a day/date: on Monday, on 4 July, on Christmas Day

Exceptions: at night, at Christmas/at Easter (the period, not the day only)

on the morning/afternoon/evening/night of a certain date: They arrived on the morning of the seventh.

It is also, of course, possible to say: this/next Monday etc., any Monday, next Monday

II. by, before

by a time/date/period = at that time or before/not later than that date. It often implies 'before that time/date':

The show starts at 6:30, so you had better be at the theater by 6:20.

before can be preposition, conjunction or adverb:

Before signing this... (preposition)

Before you sign this... (conjunction)

I've seen him somewhere before. (adverb)

III. on time, in time, in good time (for)

on time = at the time arranged, not before, not after: The 7:30 train left on time.

in time/in time for + noun = not late; in good time (for) = with a comfortable margin: Passengers should be in time for their train. I arrived at the concert hall in good time (for the concert). (Perhaps the concert began at 7:30 and I arrived at 7:15).

IV. at the beginning/end, in the beginning/end, at first, at last

at the beginning (of)/at the end (of) = literally at the beginning/end:

At the beginning of the book there is often a table of contents. At the end there may be an index.

In the beginning/at first = in the early stages; it implies that later on there was a change:

In the beginning/At first, we used hand tools. Later we had machines.

In the end/at last = eventually/after some time:

At first he opposed the marriage, but in the end he gave his consent.

Download FREE Worksheet Prepositions of Time: in, on, at - Basic (69.49 kB) contains explanations on the use of the three prepositions of time (on, in, at), and an exercise. It can be used by teachers in their classrooms or as a self-study tool. Uploading this worksheet to other websies or redistributing it for commercial purposes is strictly prohibited.

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