You won’t pass the exam _____ you don’t work hard.
| A．but | B．so | C．and | D．if |
Scientists are trying their best to_______ ways to treat the terrible disease caused by Ebola(埃博拉）．
| A．come up with | B．look forward to |
| C．talk about | D．give up |
—What shall we do this Saturday?
— it rains, we’ll have a picnic in Century Park.
| A．If | B．Unless | C．Because | D．When |
It's a pity that I didn't think of ringing you .
| A．earlier | B．earliest | C．early | D．the earliest |
To remember things accurately, we don't allow other thoughts our mind.
| A．enter | B．to enter | C．entering | D．entered |
If you travel around the world, you will be surprised at ________.
| A．how different the foreign customs are |
| B．how the foreign customs are different |
| C．how different are the foreign customs |
| D．how are the foreign customs different |