The prepositions FOR and SINCE

In this lesson, you will learn how to use the English prepositions FOR and SINCE.

I also show you some common mistakes and I correct them.

for

“for” + period of time
“for” defines a period of time in the past, present or future.
“for” describes a duration.
“for” means “From the start of the period to the end of the period.”
We use “for” with all tenses.

Examples:
He has been living in London for several months (present perfect continuous)
Jane has worked here for 10 years. (present perfect)
We will visit Spain for 2 weeks. (future simple)
Mark lived in London for 6 months. (past simple)
Today, the students are reading for 30 minutes. (present continuous)
He reads for 2 hours every day. (present simple)
I had studied French for 5 years. (past perfect)

The form is always “for” + period of time

Examples of possible periods of time are as follows:

for 10 seconds
for 20 minutes
for half an hour
for 3 hours

for a week
for a fortnight (2 weeks)
for 3 weeks
for 2 months
for 3 years
for a decade (10 years)
for a century (100 years)

since

“since” + point in time from the past
“since” defines a point in time in the past.
“since” means “From a point in the past until now.”
“since” gives the starting point. It defines when things started.

We usually use “since” with the perfect tenses:

Examples:

He has been watching TV since 7 pm. (present perfect continuous)
Mark had been writing a book since 2010. (past perfect continuous)
My parents have lived in London since 1996. (present perfect)
She had been asleep since the day before. (past perfect)

The form is always “since” + point in time

Here are some possible examples:

since 8 o’clock
since 9 am
since 10 pm
since midday
since midnight

since this morning
since this afternoon
since yesterday
since the day before yesterday
since Monday

since last Tuesday
since last week
since last month
since last year
since last summer

since 5 minutes ago
since 2 days ago
since 3 weeks ago
since a few years ago

since 2010

We can also “since” with a clause to refer to a point in the past. The tense of the clause is usually in the past simple.

Examples:

since I moved to London
since I left university
since I became a teacher

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Common mistakes with “for” and “since”

Mistake 1

“for” and “since” can both be used with perfect tenses.
But the form is NOT the same:

“for” + period of time
He has been in New York for 2 days.
(This is correct because we have used “for” with a period of time)

He has been in New York since 2 days.
(This is wrong. We cannot use “since” with a period of time)

“since” + point in time

He has been in New York since Tuesday.
(This is correct because we have used “since” with a point in time.)

He has been in New York for Tuesday.
(This is wrong. We cannot use “for” with a point in time.)

Mistake 2

To describe a period of time from the past up to the present, we use the present perfect or present perfect continuous.
We do NOT use the present tense:

I am writing for 3 hours.
I have been writing for 3 hours.

He is a musician for 30 years.
He has been a musician for 30 years.

He is a musician since 1986.
He has been a musician since 1986.

I am writing since 6 o’clock.
I have been writing since 6 o’clock.