UC知道：想知道神马，提问回答学习问题百度都知道

Although the causes of cancer ___,we do not yet have any practical way to prevent it.

来源：百度知道编辑：UC知道时间：2024/06/11 00:00:53

are being uncovered/ have been uncovering
选哪个答案对呢,为什么?
答案是are being uncovered 为什么呢?

这个题目应该是are being uncovered
原因如下:
这个句子是被动语态,the causes 作为被研究的对象,只能被研究,
如果用have been uncovering 暗示着句子的主语是人了.与前面相矛盾了 :)

have been uncovering!

Although the accountant ptomised although 1Although Freud was not the first to talk about the unconscious, Although the rich man knew very clearly that the wine and food must be eaten by the servant Although pursue what love is a blindness.But abandon the love is just sorrow languages change with the times although we seldom aware of it a local clothing store extended cretid to me although I was noly in the seventh grade although this was not allowed according to the rules of his office Although I am not the kind person who always does things according to his plan. 翻译Although research designed solely to isolate the characteristic of leaders