“Did you hear someone knocking at the do

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问题选择题

“Did you hear someone knocking at the door?”

“Yes, I did. I heard him______three times.” [ ]

A. knocking

B. knocked

C. being knocking

D. knock

答案

答案：D

选择题

David often told stories that weren't true, ________no one believed him when he told about a

deer in the schoolyard. [ ]

A. in order that

B. in order to

C. so as to

D. so that

单项选择题

气相色谱法测定海水中PCBs时，活性炭在使用前需经（）℃烘4h，装具塞玻璃瓶中，置于干燥器保存。

A、200

B、280

C、360