请教语法，剩最后一步但还是错 有同样困惑者一起探讨

Hydrocarbons碳氢化合物,, with which fruit flies perfume themselves in species-specific blends, are known to be important in courtship（动物的）求偶（现象）；求爱行为, and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of others.

(A) and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of

(B) and apparently this assists flies when they taste the hydrocarbons on prospective mates in distinguishing their own species from those of

(C) which apparently assists flies that taste the hydrocarbons on prospective mates in being able to distinguish their own species from

(D) apparently assisting flies to taste the hydrocarbons on prospective mates to distinguish their own species from those of

(E) apparently assisting flies that taste the hydrocarbons on prospective mates in distinguishing their own species from

错误选择D，正确为E，错误选择D的原因是因为those，认为补出those代替species更清晰，对于their +n.是否要补出those，还是不大明白

我的分析如下：

1）A）B)and this 结构无法从含义和语法上构成平行对称。This没有指代对象，assist应该是前面句子的伴随壮语，因此要使用现在分词形式，表示伴随

2）C）which没有指代对象，不可能修饰courtship,排除

3）在DE中排出，作出最后正确选择

但是这最后一步，我就是选择错误了：请nn指教如下问题,万分感谢：

1）assist sb in doing sth的结构，和assist … to do 有区别？

2）为什么不需要补出those（这点还是不是很明白）

以上问题应该很多g友都碰到，拿出来讨论，一起学习一下。

这道题很难 我也做错了

一点愚见：

1. others＝other species
D中those指代species ,表示species of other species 所以错

2. others本身就是一个代词，代词＋of+代词应该是不idiom的吧

同意楼上的。

另外，如果是D的话，句子就是Hydrocarbons .......,
            apparently assisting flies to taste the hydrocarbons .......结构有点古怪

感谢，感谢

快考了，有点晕，呵呵 ，大家一起继续加油！

查了手边的牛津

assist sb in doing sth的结构，和assist … to do 应该区别

同意三楼

Hydrocarbons .......,
                apparently assisting flies to taste the hydrocarbons .......结构有点古怪

Hydrocarbons .......,
                    apparently assisting flies that taste the hydrocarbons .......是不是更好些?

恩 一个是帮助taste，一个是帮助distinguish,后面更好