Learning Tenses - Step five - Present Perfect

We use the Present Perfect:

• to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc

• In sentence which includes a time clause with since , we generally prefer a past simple verb in the time clause and a present perfect verb in the main clause .

Since he became president , both taxes and unemployment have increased.

• With time clauses introduced by after , when , until , as soon as , once , by the time and the time expressions the minute/second/moment the past simple refers to past , completed events and the present perfect refers to future events .

I'll contact you the minute I've got my exam results .

• Recent events , without a definite time given .

We've missed the turning .

• Indefinite events ehich may have an obvious result in the present .

I've twisted my ankle .

• A habitual action in a period of time up to the present .

I've been jogging every morning for the last month .