A lot of research and studies have shown that Trench oil, taken out from kitchen waste, ______ the increase of cancers.
A appeals to B. attends to C. contributes to D. devotes to
The Nile River ____ flood large areas but now the water ____ produce electricity.
| A．used to; is used to | B．used to; used to |
| C．was used to; is used to | D．was used to; used to |
So difficult ____that no one could ___ a good solution to it.
| A．was the problem; come up with |
| B．the problem was; come up with |
| C．the problem was; put up with |
| D．was the problem; put up with |
When we arrived, she went straight to ___ kitchen and started to prepare ___ meal for us.
| A．the; a | B．/; a | C．the; / | D．a; the |
____they decide which college to go to, students should research the admission procedures.
| A．Once | B．While | C．Until | D．As |
The time and effort he has devoted during the past few years____ trees in that remote area is now considered to be of great value．
| A．to plant | B．to planting | C．plant | D．planting |