.
It worried her a bit ________ her hair was turning grey.
| A．which | B．that | C．if | D．whether |
--- Where does Mr. Smith come from?
--- I’m not sure, but his English _______ Australia.
| A．sounds | B．suggests | C．tells | D．says |
Facts showed that only when they united ______ the strong enemies.
| A．could they defeat | B．they could defeat | C．they did defeat | D．had they defeat |
Don’t lose heart. It won’t be long ___________ you catch up with others.
| A．since | B．until | C．as | D．before |
John must have forgotten to return the magazine to the library yesterday, _________?
| A．mustn’t he | B．hasn’t he | C．haven’t he | D．didn’t he |
--- Does _____ of these two buses go to the station?
--- You can’t get to the station by __________ of them.
| A．both; both | B．neither; neither | C．any; any | D．either; either |