We have very strict quality control and anything imperfect is ____, so customers feel secure about our products．
| A．denied | B．rejected | C．deserted | D．refused |
Hot __________ the night air was, we slept deeply because we were so tired after the long journey.
| A．although | B．as |
| C．while | D．however |
__________ the police thought he was the most likely one, since they had no exact proof about it, they could not arrest him.
| A．Although | B．As long as |
| C．If only | D．As soon as |
__________ H7N9 is a deadly virus, it is still safe to eat thoroughly-cooked chicken.
| A．Until | B．While |
| C．If | D．Since |
__________ you may have, you should gather your courage to face the challenge.
| A．However serious a problem |
| B．Whatever serious a problem |
| C．However a serious problem |
| D．No matter how a serious problem |
In China, Some people are quite well-off __________ some live in terrible conditions, especially in remote areas.
| A．though | B．as |
| C．while | D．when |