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;
B:unless
C:until
D:when;
正确答案是：
同类题型
Who is the tallest boy —It ______ be John.. John is of medium height.
This is the only one of the oldest customs that ________ down in this area so far
I think students should _______ to have at least one hour a day for sports.
Busy as Tom is, exercise has always been______his work.
Simon has got 95 points in the mathtest!——Wow!______________ he has made!