We must keep a positive attitude toward the future______we may encounter some difficulties.
| A．however | B．as if |
| C．even if | D．since |
The workers were working from 7:00 a.m. to 7:00 p.m. that day, only ____ once at noon to have their lunch.
| A．to stop | B．stopping |
| C．to have stopped | D．having stopped |
If the weather had been better, we could have had a picnic. But it ____ all day.
| A．rained | B．rains | C．has rained | D．is raining |
-_____ you read the story?
-Yes. I _____ it at school.
| A．Have; read | B．Did; read |
| C．Have; have read | D．Did; have read |
There is only one more day to go ____ your favorite music group play live.
| A．since | B．until | C．when | D．before |
-Must I turn off the gas after cooking?
- Of course. You can never be ______ careful with that.
| A．enough | B．too | C．so | D．very |