单选题Theastronautdidmanyexperimentsinth

单选题 The astronaut did many experiments in the spaceship, ________ much help for knowing space．A.which we think it isB.which we think are ofC.of which we think isD.I think which is of

B解析从选项中可知，定语从句中有一个插入语we think，而插入语一定是紧跟在引导词之后的。sth．be of+n．＝sth．be+adj．(此结构中的名词和形容词是同源的)，因此选B项。从句若去掉插入语，就是which are of much help“有很大帮助”。这里从句的谓语动词用复数，说明将experiments看作了先行词，也可以将主句整句话看作先行词，那么从句谓语动词就应该用is了。

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