2019年mpa考试英语真题——介词和介词短语477

{01}Most of the students feel nervous when they are reminded that it will be about half a year ________ they take the national college entrance examination．
A.since
B.that
C.before
D.until
解析：
本题选C。
{02}They kept digging ________ they must have known there was no hope．
A.as
B.while
C.when
D.unless
解析：
本题选C。