Is it necessary that the tense of the entire sentence should be the same?
In the following sentence
I declined the invitation not because I did not want to go, but because I have no time.
According to my book have must be converted to had, because the sentence is framed in the past tense.
But I think the above sentence is correct, because if I never have time is a fact, then it (I never have time) will be true in all the tenses, and hence use of present indefinite tense is not wrong