83.        (28949-!-item-!-188;#058&004110)

The number of plant and animal species that humans are known to have forced to extinction in the last half millennium is over 800.

(A) humans are known to have forced to extinction
(B) humans are known as having forced to become extinct
(C) humans are known for forcing to become extinct
(D) are known that humans forced to become extinct
(E) are known as having been forced to extinction by humans
请问这里问什么要选A，be known to do sthing 是什么意思，谢谢！

我最讨厌看到 human 做名词，所以把题目改了，不那么刺目：

The number of plant and animal species that human beings are known to have forced to extinction in the last half millennium is over 800.

(A) human beings are known to have forced to extinction
(B) human beings are known as having forced to become extinct
(C) human beings are known for forcing to become extinct
(D) are known that human beings forced to become extinct
(E) are known as having been forced to extinction by human beings
请问这里问什么要选A，be known to do sthing 是什么意思，谢谢！

B 错是因为累赘。C 错因为 known for 的意思是“以 . . . 出名”。D 错因为语无伦次。E 错也是因为累赘。

A 虽然面目可憎，但是尚无大错。

Known to do something 就是按字母来解释。不明白哪里？

句子主干：The number of plant and animal  species is over 800.

that后面的句子是修饰species的吧
那还原过来是什么？human beings are known to have force the species to extinction. 这个是什么意思,are known to do ...的意思不明白

我理解be known to 是这样用的
He was known to have invented many things．
human beings are known to have force the species to extinction. 是不是就是说人类因为让那些玩艺儿灭绝了而出名？感觉句子的重心转移了

是的，还原得对。

Are known to have done something 就是”过去曾经作过“。这个 known to have 是被动式，翻译为中文的时候应该改做主动式的，所以最好这样翻译：”我们知道人类过去曾经逼到很多动、植物绝了种“。

Thanks!!

多谢高手解释。很清楚