Itnever_____humansuntilthemid­1990sthatsomeanimalscanbecloned

发布时间：2020-08-04 07:22:40

It never _____  humans until the mid­1990s that some animals can be cloned.A.occurB.is occurredC.occurred toD.occurred

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C解析试题分析：It occurs to sb that 某人突然想到...，occur to 发生，突然想到。。。句意：直到20世纪中期人类才突然想到克隆出一些动物。考点：考查句型It occurs to sb that

点评：注意句型的识记。
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