Page 55 - Basic English Usage

55 61-62

61 before (adverb)

We can use before to mean ‘at any time before now’. We use it with a
present perfect tense (have + past participle).
Have you seen this film before?
/'ve never been here before.
Before can also mean ‘before then’, ‘before the past time that we are
talking about’. We use a past perfect tense (had + past participle).
She realized that she had seen him before.

In expressions like three days before, a year before, a long time before,
the meaning is ‘before then’. We use a past perfect tense. (See 20.4 for
an explanation of the difference between before and ago in these
expressions.)
When | went back to the schoo! that | had left eight years before,
everything was different.

62 before (conjunction)

clause + before + clause
before + clause, + clause

We can use before to join two clauses.
We can either say: A happened before 8 happened
OR Before B happened, A happened.
The meaning is the same: A happened first.
Note the comma (,) in the second structure.
/ bought a lot of new clothes before | went to America.
Before ! went to America, | bought a lot of new clothes.
He aid military service before he went to university.
( = He did military service first.)
Before he did military service, he went to university.
( = He went to university first.)

In a clause with before, we use a present tense if the meaning is future.
(See 343.)
ffl telephone you before you leave.
(NOT ... befere-yeu-witHeave-)

3 In a formal style, we often use the structure before + -ing.
Please put out all lights before leaving the office.
Before beginning the book, he spent five years on research.