题目内容
He was observed ________ into the house and helped himself to find what he liked before the owner came back.
[ ]
A.to slip
B.slip
C.slipping
D.slipped
答案:A
解析:
解析:
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本题考查observe的用法.observe sb.do sth.用于被动形式时,要加不定式符号to,即sb.be observed to do sth.B项前没有to; C、D项也都不符合这一用法. |
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