The key the earth is to change the way we live.
| A．to save; / | B．to saving; / |
| C．to save; how | D．to saving; how |
______this difficulty is overcome, other problems will be easy to solve.
| A．For | B．Whether | C．Once | D．Though |
Don’t mention that at the beginning of the story, or it may ____the shocking ending.
| A．give away | B．give in | C．give up | D．give off |
---How long ____ you ____ in Singapore?
---For just the weekend． I’ll be back next Monday morning．
| A．have; stayed | B．are; staying | C．did; stay | D．do; stay |
Rather than ______ on a crowded bus, he always prefers _____a bicycle．
| A．ride; ride | B．riding; ride | C．ride; to ride | D．to ride; riding |
The man ______ was a friend of mine．
| A．you just talked to | B．whom you just talked to him |
| C．who you just talked to him | D．which you just talked to |