---Tell us, Mark, what is the cause of the American Civil War?
---Well, is it _______the black slaves wanted freedom?
| A．how | B．why |
| C．because | D．when |
The students left the room _______all the lights on.
| A．with | B．and | C．but | D．when |
Roses need special care ______they can live through winter.
| A．because | B．so that | C．even if | D．as |
Only in this way ____to make an improvement in the operating system.
| A．you can hope | B．you did hope | C．can you hope | D．did you hope |
They ___________to put their hearts into study..
| A．have made their minds | B．have made their mind |
| C．have made up their minds | D．have made up their mind |
It was a _______story, and we all got ________.
| A．shocking; shocking | B．shocked; shocked |
| C．shocking; shocked | D．shocked; shocking |