___ most of the earth’s surface is covered by water, fresh water is very rare and precious.
| A．As | B．Once | C．If | D．Although |
After he retired from office, Tom ___ painting for a while , but soon lost interest.
| A．kept up | B．took up | C．sped up | D．cleaned up |
At first ___ , the bag seems made of real leather, but actually it is just an imitation.
| A．sight | B．look | C．appearance | D．view |
Can you tell us what horses _______?
| A．feed on | B．live on | C．feed by | D．live by |
He said that he didn’t know ______ to deal with the matter, so I left.
| A．what | B．when | C．where | D．how |
The way of life he was used to _______ when he came to study in America.
| A．change | B．changed | C．changing | D．being changed |