Question

麻烦哪位高手教教我这道题怎么做？选择哪个？为什么？

Scientists interested in the problem ( )at it for year. A.has been working B.has worked C. have been working D.working

Answer 1

选c啊，for year是现在完成进行时 ，用have /has been working ,scientists是复数形式，所以用have ，呵呵，采纳一下哦

Answer 2

选C。
句子的主干是Scientists have been working on it.
interested in the problem做scientists的定语。
for years 表示时间段前面要要用完成时
此句子表示到说话这一刻起这个动作还在进行，所以用现在完成进行时。
如果到说话时已经结束则要用现在完成时。

Answer 3

选C。
主干是Scientists have been working on it.
interested in the problem做scientists后置定语。
选完成时则是因为后面有for years。