By Present perfect, Resume

Present perfect vs simple past has nothing to do with duration, but with time. If an action or event is definitely completed in the past (that is, it is clearly finished and there is no need to explain to the reader that it is finished), then use simple past tense: your job is finished and your...

First, the sentence with the question mark is fine. All three pairs show the same relationship, but with the third pair reversed! The ones with "been -ing" emphasize the duration. They suggest a descriptive attitude toward an activity which "has been going on". We should feel the passage of...

You've selected a verb ('to work') for which the difference between the present perfect and the present perfect continuous is practically insignificant. There are other verbs for which one of these is possible, and the other, anomalous. For these, it may be easier to understand the difference...

Hello, June. I can point out some improvements for these sentences. 1. In the first sentence, you begin with the past progressive ("was studying"). That implies action that has not yet finished. Then you move on to the past perfect ("had known"). It is not possible for the past perfect to...