_____ you may have, you should gather your courage to face the challenge.
| A．However serious a problem. | B．What a serious problem. |
| C．However a serious problem. | D．What serious a problem. |
The movie Life of Pi is so attractive that it holds the audience's curiosity ________ the story reaches the end.
| A．until | B．before |
| C．after | D．when |
________ H7N9 is a deadly virus, it is still safe to eat thoroughlycooked chicken.
| A．Until | B．While |
| C．If | D．Since |
I will accept Guy coming with us, ________ he pays for his own meals.
| A．only if | B．so that |
| C．ever since | D．even though |
Scientists are warning that ________ emissions of carbon (碳排放) are cut, we could be heading for an environmental disaster.
| A．before | B．as |
| C．unless | D．in case |
——Did you inform Helen of the plan put forward at the meeting?
—Of course. ________ I saw her.
| A．So long as | B．If only |
| C．The moment | D．Any time |