Analyze the following statementes about teaching tense and time in Brazilian EFL classrooms:

I. Brazilian learners tend to confuse the present perfect with the simple past because of Li interference.

II. Explicit instruction on tense/time distinction is unnecessary because learners acquire it naturally.

III. Emphasizing communicative contexts helps learners understand tense use more effectively.

IV. Aspectual distinctions are essential for explaining English verb usage.

Which ones are correct?