4. In cold-water habitats, certain invertebrates and fish convert starches into complex carbohydrates called glycerols, in effect manufacturing its own antifreeze.

(A) in effect manufacturing its own antifreeze

(B) effectively manufacturing antifreeze of its own

(C) in effect manufacturing their own antifreeze.

(D) so that they manufacture their own antifreeze

(E) thus the manufacture of its own antifreeze

答案是C 但是D为什么不可以呢?

在webster上 in effect的意思是virtually, almost entirely....好像d更合适哦

请大牛帮忙解答一下. 以前讨论过吗?如果有大家谁知道能不能给我连接. 谢谢

Choice A and B are incorrect because the pronoun its does not agree in number with invertebrates and fish, the noun referents. B also distorts the intended meaning of the sentence by making a statement about how effectively the invertebrates and fish manufacture their own antifreeze.

Choice C is correct. In D and E, so that they manufacture and thus the manufacture do not form logical connections with the rest of the sentence, and its in E is incorrect. This is an easy question.