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How accurately can you use for and since?

✔ Mr Dimitrov has been a smoker for 10 years.

The use of ‘for’ and 'since’ is something which confuses many students of English. In the examples above, they have been used incorrectly. How should you use them?

  • For is used to say how long something has been happening for: for 10 years, for some time, for 15 minutes, for a while.
  • Since is used to say when something started: since last night, since 2005, since birth, since last week, since arriving in Australia.

Both these prepositions are commonly used to describe events happening over a particular period. They are most often used with the present perfect tense.


Present perfect

The present perfect verb tense is a very important tense in English, but it gives speakers of some languages a difficult time. That is because it uses concepts or ideas that do not exist in those languages.

In fact, the structure of the present perfect is very simple: it refers to an action or state that either occurred at an indefinite time in the past (e.g., we have talked before) or began in the past and continued to the present time.

Grammar revision:

How do you make a present perfect verb tense?

The answer is simple: Subject  +  have/has + past participle of the main verb.

Example: Mr Jones has taken his medication.

Present perfect is often combined with for OR since OR over.

For is used to describe an amount of time (eg: for one week).

Since is used to refer to the start of a period of time (eg: since September 2018).

Over is used to express a change in condition, or to describe a repeated event. Examples:

  • The patient's condition has deteriorated over the past 3 months. (change in condition)
  • The patient has presented several times over the last year. (repeated event)

Compare the usage below and note the time markers used:

  • Mr X has had depression since the death of his wife last year.
  • She has visited the clinic every week for 2 months.
  • He has experienced seizures 3 times over the last 6 months.

Handy tip:

When using time markers such as:

  • For the last...
  • For the past...
  • Over the last...
  • For the next...

ALWAYS use the article ‘the’, with these expressions.

Now try this quiz to check your understanding:

Some of these sentences use incorrect verb tenses. Can you spot them?

  1. Mr X has had hypothyroidism since 2007.
  2. Mr X is smoking two packs of cigarettes a day for the past 25 years.
  3. Over the past week, she remains free from pain.
  4. The ulcer under her tongue has been present for more than one year.
  5. Mr X has had type 2 diabetes for 10 years
  6. Mr is a patient of mine since 2013.