单选题 It goes without saying that pollution ______ a serious threat to the continued existence of some species living on earth.
A. poses B. imposes C. provokes D. evokes

【正确答案】 A

【答案解析】pose：造成，引起(困难)；impose：把……强加，常用搭配是impose sth. on sb. ；provoke：引起，挑衅；evoke：引起，唤起(感情、记忆)。