题目内容
16.This scientist is known _______ on this problem for about ten years.( )A. | to work | B. | to be working | ||
C. | to have been working | D. | to have been worked |
分析 人们知道这位科学家已经研究这个难题差不多有十年了.
解答 答案:C
短语搭配be known to do sth做某事被人了解,被人所熟知;句中for about ten years是表示持续的时间段,是完成时态的时间状语;work on后接宾语,要用主动.故选C.
点评 动词不等式是非谓语动词的一种,也是英语中比较活跃的一类结构.通常用来作主语,宾语,表语,定语,状语等.学习时要全面掌握,熟练运用.

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