prep2－83

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

答案是A ，我第一次选了E，第二次选了B，反正是很糊涂，不知道到底是什么意思

be known as + doing 错。 应该是名词；排除BE

D选项species that are known that...两个从句连用，错；

for+doing 大多为错，排除C

humans are known to have forced these species to extinction