prep2-83看了贴还是不明白

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

这题我超级晕。have 在这里做什么成分？ 怎么又会有force sth to sth？超级不明白！！

大牛给我解答一下吧？！万分感激

先谢谢解答，那就说have 在这里表完成喽。就是说“人类已经使那些species灭绝了”？应该这样翻译吧

可是我又有个问题，如果改成humans have been known to force to extinction，对么？为什么这个“完成”要在“be known to”的后面呢？我总觉得比较奇怪。

还望不厌其烦，再给解答一下