大全885 SECTION５-３，请教！！！

yangyang198313

3.     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（B）

(E) to act as a sentinel sounding

这里由于结构平行选B,但是这样整个句子的结构就是such as defending....,acting as...and sounding....,and scouting....and roosting.....我想请问一下，这里的acting as...and sounding....,是做伴随状语修饰前面吗，还有such as doing A ,doing  B ,and doing C ,zh这里怎么这么多ＡＮＤ啊　

ericxixi

就是最基本的平行结构只不过ETS把它弄得很复杂的样子,A,B,andC 结构

yangyang198313

以下是引用ericxixi在2006-3-4 18:31:00的发言：
就是最基本的平行结构只不过ETS把它弄得很复杂的样子,A,B,andC 结构

那这里的Ａ，ＢANDＣ分别是哪部分啊 能说的详细点吗