1 . We all need to get involved in saving energy ________ it's at work, at home, or at school.

A．unless

B．once

C．whether

D．because

2 . In the dark street, there wasn’t a single person ________ she could turn for help.

A．that

B．to whom

C．who

D．from whom

3 . 【2018·北京】_________ we don’t stop climate change, many animals and plants in the world will be gone.

A．Although	B．While
C．If	D．Until

4 . （2020年北京卷）Oliver says if you’re lucky enough to have someone close to you who enjoys cooking, ask them __________you can join in when it’s possible. (用适当的词填空)

5 . Your ability has never been in doubt — the question is ________ you are prepared to work hard.

A．that

B．whether

C．what

D．if

6 . Jane moved aimlessly down the tree-lined street, not knowing ________ she was heading.

A．why	B．where
C．how	D．when

8 . The river is seriously polluted, ________has caused much public attention. （用适当的词填空）

10 . They are the people________house caught fire. （用适当的词填空）