The Audubon Society and other conservation groups, concerned over what they have perceived to be the serious threatening of the environment as posed by the policies of the government, are preparing for a major political effort.

(A) have perceived to be the serious threatening of the environment as

(B) perceived as the serious threat to the environment as

(C) perceive being the serious threat to the environment

(D) are perceiving as the serious threatening of the environment

(E) perceive as the serious threat to the environment

请问一下，perceive这个时态对吗？为什么不用过去式呢 ？谢谢！

这里的时态正确。

整个句子的主句是：The Audubon Society and other conservation groups are preparing for a

major political effort.基本时态是现在时。

其中，concerned over what------中concerned是adj.

Many politicians are more concerned with power and control than with the good of the people.

这种题目，我遇到，必错

我做题就是看主谓，和画线部分，然后就找语法点，这题我一看到，肯定立马就认为用过去时态，和concerned保持一致，然后在30秒内恐怕就已经选了B了，ETS现在招数真多啊