____some doubt among scientists about the cause of cancer.A.It existsB.There exists C.There is exist

题目简介

____some doubt among scientists about the cause of cancer.A.It existsB.There exists C.There is exist

题目详情

____some doubt among scientists about the cause of cancer.
A.It existsB.There exists C.There is existingD.It is existing
题型:单选题难度:偏难来源:不详

答案

B
考查特殊句式。There be结构中的系动词换成其它的系动词如exist, happen,seem等;系动词是没有进行时的。所以排除CD。句意:在科学家中对于癌症的原因存在着一些怀疑和争论。

更多内容推荐