Question

【題目】You should inspect the wheels regularly, and replace them ______ they cause you trouble.
A.while
B.when
C.before
D.until

Answer 1

【答案】C
【解析】句意：你應該在出事之前經(jīng)常檢查車輪并及時更換。A.while”當.....時，然而”；B. when“在.......時候，隨著”；C.before 在......之前“；D. until”直到.....才“。故選C。