that or when?

A or C

Eh... So you think they are both right? The answer is A. I can understand the explanation that 'those days' here is a temporal adverbial here. But why is C wrong? Or if they are both right, why is A fitter than C here?

Sorry,here I find a new question. Is it fitter or more fit? I mean suitable.

rpsh So you think they are both right?

Both are extremely common. I don't see that either is really 'fitter' or 'more fit' than the other, although I suspect that there must be a prescriptivist rule that is still kicking up the dust in some far-flung corners of the EFL world.

This is an exam question. So there must only be one answer. However, after I read a lot of book, I start to have something instinct, or language sense that is always referred by my middle school teacher, who asked us to do exercise with language sense, rather that the knowledge of grammar. Do you solve the problem with such sense?

rpshThis is an exam question. So there must only be one answer.

Not true. We meet many extremely faulty examination questions here.

rpsh I start to have something instinct, or language sense that is always referred by my middle school teacher, who asked us to do exercise with language sense, rather that the knowledge of grammar.

Alas. If it were not for attending the exam, I would't be entangled by such questions... Thank you.