单选题
18.
It seems oil______from this pipe for some time. We'll have to take the machine apart to put it right.
A、
had leaked
B、
is leaking
C、
leaked
D、
has been leaking
【正确答案】
D
【答案解析】
根据句中的时间状语“for some time”，空格上的时态可有两种选择：现在完成时与现在完成进行时。
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