题目内容：

Frank,look at that ____是填 a set of keys还是填set of keys

优质解答

Frank,look at that ____
选择ste of keys
理由：
名词前有指示代词,物主代词,不定代词或名词所有格修饰,不用冠词.
I like this picture better.Is that your book
Take their chairs away!I do not have any money on me.
As time went on,Einstein's theory proved to be correct.
这道题里有指示代词that,不可以说that a set of keys..

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call••••at •••什么意思