We should take part in such activities in future _____ we did yesterday.
| A．which | B．as | C．that | D．than |
If we ________ now to protect our mother river ---Li Jiang River , we ‘ll live to regret it.
| A．haven’t acted | B．won’t act |
| C．don’t act | D．hadn’t acted |
Only after Mary read her article a second time _____the spelling mistakes.
| A．did she notice | B．she noticed |
| C．does she notice | D．she has noticed |
--- Tom , why didn’t you answer my call yesterday afternoon?
--- Sorry , I didn't hear the phone . I ___________ asleep.
| A．must be | B．must have been |
| C．could be | D．should have been |
If you want to change for a red one you'll have to pay ___________ $ 20.
| A．another | B．other | C．more | D．each |
September 18, 1937 is a day _______ all Chinese will remember forever.
| A．when | B．what | C．不填 | D．why |