大全-693 concerned为什么是形容词？

wowojia3010

1.        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）

(E) perceive as the serious threat to the environment

详解中说concerned在这里是一个形容词，按句意讲The Audubon Society and other conservation groups 应该是concern的主语，concerned不是过去分词。那这究竟是怎么一个用法？糊涂了

wowojia3010

外加大全696

1.        The Baldrick Manufacturing Company has for several years followed a policy aimed at decreasing operating costs and improving the efficiency of its distribution system.

(A) aimed at decreasing operating costs and improving

(B) aimed at the decreasing of operating costs and to improve

(C) aiming at the decreasing of operating costs and improving

(D) the aim of which is the decreasing of operating costs and improving（A）

(E) with the aim to decrease operating costs and to improve

解释也说这里aim不是过去分词，而是与at 一起构成一个形容词短语。究竟如何理解呢？

Zeldaw

恩，很深奥。手头没有语法书，等待NN解释吧