时态填空。 1. Listen! Someone _______ (sing) in the next room. 2. There _______ (be) an exhibition of art in the museum tomorrow. 3. Everyone in our class _______ (enjoy) music very much. 4. It's so cloudy. I think it _______ (rain). 5. We are looking forward to _______ (go) sightseeing. 6. When is the best time _______ (vis it) your hometown? 7. The thief tried _______ (run) away but the policemen _______ (catch) them in the end. 8. Is it difficult _______ (finish) _______ (write) the article in one day?