问题

They were walking along the shore _______ a huge wave appeared out of nowhere, sweeping them out to sea
A:as
B:while
C:when
D:though
B:while
C:when
D:though
正确答案是:
同类题型
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Don’t let yourself be by a small failure in the experiment Try again.
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The baby, _____health was ruined after taking the medicine, was only one year old.