WE ..................................... ENGLISH FOR FIVE YEARS.(STUDY)FILL IN WITH SUITABLE TENSES GIVEN IN BRAKETS.
The most correct would be to use the present progressive tense, "We have been studying English for five years." That tense indicates that the action began in the past, but is still continuing. You could also say "We have studied English for five years" which would be the present perfect, but indicates the action may or may not be continuing -- usually it means that the action has ended. You could also say "We had studied English for five years" which is the past perfect, also indicating that the action is no longer continuing. With the last two examples, you would really need to have additional information to know whether or not to use one of them. Since you do not have that, I would go with the first example - the present progressive - "We have been studying English for five years."
To be more specific, "We had been studying English for five years when we decided to visit England and really practice speaking." The action begins and ends in the past. Or, you might have something like "We have been studying English for five years, but we are not very fluent." This indicates the action began in the past, may or may not still be going on, but there is a subordinate idea that goes along with it." You have not been given any additional subordinating information, so it's hard to say 100% which one to choose -- any of these is grammatically correct, though.
There are other possibilities as well:
- We could have studied English for five years, but we decided to study French instead.
- We might have studied English for five years if we had remained in England.
- We would have studied English for five years if we had lived in the United States longer.
- By this time next year, we will have studied English for five years.
Hopefully, I have not totally confused you -- but these are several options with additional information.