1 . It is still a mystery ______ caused the infectious virus to spread quickly in this hospital.

A．which

B．where

C．what

D．that

2 . 最重要的是这位老人对偏远地区教育事业的无私奉献。 (用what引导的主语从句翻译句子)
__________________________________________________________________________

3 . 最重要的是人们为了修筑这些梯田并种植水稻，而采取的一种顺应自然和谐劳作的方式。(汉译英)

4 .        is a fact        smoking is a danger to our health.

A．What; that

B．It; that

C．What; which

D．It; which

5 .         made my sister angry yesterday was that her new mobile phone was stolen.

A．What

B．That

C．It

D．Who

6 . ________ the whole family get together on the Moon Festival is deeply rooted in Chinese culture.

A．What

B．When

C．How

D．That

7 . ________ smartphones cause problems in schools is not a novel observation. It is roughly a decade since they became ubiquitous (无处不在的) in the UK.

A．Where

B．That

C．Which

D．What

8 . ________ the majority of the team members got nervous about the coming competition urged the team leader to relax them through a series of interesting games.

A．What

B．How

C．Whether

D．That

9 . ________ is often the case, I assume, is the fact that when looking back, the bittersweet senior life is always one’s highlight in pursuit of dream.

A．As

B．Which

C．That

D．What

10 . It is a fact that ______ some people show to others is completely different to leave a good impression.

A．which

B．what

C．how

D．why