2019年mpa考试英语真题——连词566

{01}Many people believe we are heading for environment disaster ____ we basically change the way we live.
A.if
B.but
C.unless
D.once

解析：
本题选C。

{02}As the experts tell us, we can pass on the flu _____ we realize we have it. A.before
B.since
C.while
D.when
解析：
本题选A。