There’s no way of knowing why one man makes an important discovery another man, also intelligent, fails.
| A．since | B．If | C．as | D．while |
What a useful dictionary! How long_____ you_____ it?
| A．will, have | B．did, have |
| C．have buy | D．have had |
During the charity walk, people have to walk_____ country parks and_____ hills and mountains.
| A．over, through | B．through, on |
| C．through, over | D．in, on |
All the children should be helped when they are ______. They should also be treated with ______.
| A．sickness; kind | B．sick; kindness |
| C．sickness; kindness | D．sick; kind |
The old man is ______ weak ______ say any words.
| A．too; to | B．so; that | C．very; that | D．so; to |
We should try our best _______ poor children _______ clean water and food.
| A．to provide; with | B．to provide; to |
| C．provide; to | D．provide; with |