----- What made you so upset?
----- ______ my new bike.
| A．Lost | B．Losing | C．Because of losing | D．Since I lost |
________ it is, the boy never seems to be able to finish it off.
| A．However interesting a book |
| B．Whatever interesting a book |
| C．How interesting a book |
| D．What an interesting book |
The new system needs to be in operation for five months ________ it can be updated.
| A．as | B．while |
| C．before | D．once |
We can't wait any longer ________ we'll miss the plane.
| A．or | B．but |
| C．so | D．yet |
House prices vary from place to place and are usually high ________ there are famous schools.
| A．when | B．since |
| C．where | D．whether |
It will be another 50 years ______ our country is expected to reach the level of a medium developed country.
| A．since | B．before |
| C．that | D．when |