— According to my grandma, it is a good idea to eat chicken soup when you have a cold.
— ________, scientists agree with her.
| A．Sooner or later | B．Once in a while | C．To be exact | D．Believe it or not |
When he found many people were gathering there, he went to see what __________.
| A．happened |
| B．would happen |
| C．has happened |
| D．had happened |
He __________ that until he __________ the directions once again.
| A．didn't understand ； had read |
| B．hadn't understood ； read |
| C．understood ；had read |
| D．understood ； read |
When they met again in New York, ten years __________.
| A．passed |
| B．was passing |
| C．had passed |
| D．has passed |
__________ the time the firemen arrived, the building had been burnt to pieces.
| A．At |
| B．Till |
| C．When |
| D．By |
__________ industry develops quickly, more and more rivers are being polluted.
| A．When |
| B．As |
| C．After |
| D．With |