问题

If you feel tired out and unable to think clearly,that is________you have to get a rest[ ]

A: why
B: when
C: whether
D: what

正确答案是：

同类题型

The first decade in the 21st century is the one ______ many significant advances are made in China

下列各句中，表达得体的一句是

Please remember _____ the lights when you leave.

smoke any more, Ralph ! It is very bad for your health! –I know I should give up smoking, but ________

Huang, would you mind if I ______ your Pipa for the coming competition?—_________. [ ]