The thing which confuses me is the usage of “in” and “for” in the following examples.
I think the following description of the meaning of these sentences is correct.
1) It has rained for the last week. (”for” represents a continuing action)
2) It has rained in the last week. (”in” represents a once-off action)
For = conveys an action lasting the whole period of time.
In = indicates that something happens within this period of time but the action doesn’t last the whole period.
My first question is:
Does “in” imply only one instance (occasion) of a certain action or more? That is, does the sentence “It has rained in the last week” say that there was only one instance when it rained or can it mean that there was more than one instance when it was raining? (I suspect that it conveys only one instance of some action, but I am not sure)
Now, the difficult part begins. I have noticed that with some verbs “in” carries the meaning of completeness. For example,
3) I have learnt English in the last 3 years. (It means that I have completed my English studies and now I know English.)
The main question:
It makes me wonder why 3) can’t be understood as “I have been involved (maybe only once) in the process of learning English in the last three years. But I haven’t mastered it.” In other words, why can’t 3) be understood as 2)? (I hope you don’t think that I mean the lexical meanings of “to rain” and “to learn”. I mean why can’t 3) mean that I learnt English only once during that period?)
I hope I managed to make my issue clear to you.