For example, when using "since", you should use "present perfect":
Mr Smith _ _ _ the company since 1990.
- has run
- is running
Is there any reference on similar rules, guiding principles or hints? sometimes things get mixed up for me when choosing the correct form of verb tense (past/present continuous/perfect/simple...).
Also any other rules on similar cases (other than verb tenses) are also welcome : )
I tried doing some research, but haven't found much, probably I am not using the right search terms. Any hints on this are also welcome, I will do my research homework.
I have an English test tomorrow, English is not my mother tongue (you probably guessed).
Edit: What I am asking for can be abbreviated to this specific question:
Is there any reference that contains rules on when and where should one use a specific tense/aux. verb over another?