1 . Scientific studies show that laughter produces chemicals to make people feel better, ________ means clown doctors can be helpful.

A．which

B．that

C．what

D．where

2 . Their business came from a few big publishers, all of________books they printed.

A．whose

B．which

C．whom

D．that

3 . Some species can be very small, like bacteria and viruses,       are so small that we cannot see them with only our eyes.

A．who

B．that

C．which

D．where

4 . Celeste Ng’s latest book,           plot is quite new and original, has received a lot of attention.

A．which

B．where

C．whose

D．that

5 . I walk through the doors into the waiting area,         there's a familiar atmosphere of boredom and tension.

A．which

B．that

C．whose

D．where

6 . The movie was directed by a famous writer. The movie won many awards. (用非限制性定语从句改写句子)
____________________________________________________________________________

7 .          is well known to us, Tianjin has a history of more than 600 years.

A．As

B．What

C．Where

D．It

8 . The fire started on the first floor of the hospital,          patients were elderly people.

A．many of whose

B．whose many

C．many whose

D．many of whom

9 . My brother’s bedroom is always a mess, and he can never find anything,          is very frustrating.

A．where

B．whom

C．when

D．which

10 . Volunteers in China, _______ are playing an increasingly important role in many fields, are actively participating in the battle against COVID-19 at present.

A．which

B．that

C．who

D．where