正确答案: A

to keep

题目：The officer asked him ________ a sharp lookout for the fishing boats

解析：A

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学习资料的答案和解析：

[单选题]Where ________ you ________?

have/been

[单选题]单螺杆泵与三螺杆泵相比( )。

对杂质较不敏感