OG11REVIEW1

1. Some bat caves，like honeybee hives，have residents that take on different duties such as defending the entrance，acting as sentinels and to sound a warning at the approach of danger, and scouting outside the cave for new food and roosting sites．

(A)  acting as sentinels and to sound

(B)  acting as sentinels and sounding

(C)  to act as sentinels and sound

(D)  to act as sentinels and to sound

(E)  to act as a sentinel sounding

Parallelism + Agreement

The original sentence has an error in parallel structure．It starts by using the-ing (participial) form to list the bats’ duties．Defending，acting，and scouting all use the same-ing form．The phrase to sound uses the to-(infinitive)form，and so it is not parallel．The word sounding is required in this sentence

A  To sound is not parallel to defending, acting，and scouting．

B  Correct．This sentence has sounding, which properly parallels defending, acting, and scouting．

C  To act and sound are not parallel to defending and scouting．

D  To act and to sound are not parallel to defending and scouting．

E   Introduces agreement error(a sentinel)；to act is not parallel to scouting．

The correct answer is B．

doing, doing and doing, and doing and doing.按照解释这是平行，可讲平行时没有这种形式啊！请高人解释、大家探讨！

自己顶一下！

看句意：

acting...and sounding...都是讲作为警卫的动作

scouting...and roosting... 都是讲活动的范围

就像解释里面的Defending，acting，and scouting all use the same-ing form．是 ing, ing, and ing的形式

今天又看了题目，最后的roosting作形容词用修饰sites与food平行。所以此平行结构应为doing, doing and doing, and doing!

更加的晕了！

这题要注意区别大小平行. 我的理解是:

Some bat caves，like honeybee hives，have residents that take on different duties such as defending the entrance，acting as sentinels and sounding a warning at the approach of danger, and scouting outside the cave for new food and roosting sites．

大平行:defending, and scouting

两个小平行:

1)acting...and sounding...修饰defending the entrance

2)new food and roosting sites 这里的roosting是形容词.

谢谢业余侠客的回答，很有道理，但我又有一个问题，就是(D)  to act as sentinels and to sound为什么不对呢？

因为这是他们是另一个层次的平行了，用不定式又有什么不合理的地方！还是有些晕！

这道题的出题点是不是平行，然后是不定式和动名词之间的区别呢？解释中并别有提出后者？

请高人解释一下