问题

The air pollution is terrible.—It will be worse_____ we take action to protect the environment.

A:if
B:unless
C:until
D:when;

正确答案是：

同类题型

The big house was burnt down in the big fire, nothing ________[ ]

Oh, it’s you! I ______ you. — I’ve just had my hair cut and I’m wearing new glasses.

English has a large vocabulary, _______?—Yes. Know more words and expressions and you will find _______ easier to read and communicate.

“Simpler” books are the foundation ______students build a lifelong habit of reading and further the actual skill ofreading for longer and stronger periods of time

They knew her very well. They had seen her____ up from childhood. [ ]