On reaching home I discovered that I__________ my keys at the office.

A．left

B．have left

C．was left

D．had left

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参考答案

【译文】到家的时候我发现我把钥匙丢在办公室了。
【解析】本题考查时态的选择。根据“I discovered”可知，整句为过去时态。钥匙忘在办公室发生的时间早于发现的时间，故应该选择过去的过去，即过去完成时态，故选D。

1 By the time she leaves the stage next month, she __________ for sixty years.

A．will have performed

B．has performed

C．will be performing

D．will perform

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2 I appreciate __________ to your school to give a lecture.

A．to be invited

B．to have invited

C．having invited

D．being invited

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3 __________ , follow the directions on the bottle carefully.

A．When taken drugs

B．When taking drugs

C．When one takes drugs

D．When to take drugs

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