[E]OG-03，请指点！

excellent

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
E.to act as a sentinel sounding

OG上解释说acting,sounding应该与defending,scouting并列，但我的理解是act和sound这两种行为应该是defending的补充或定义，大家觉得呢？

假设我的理解是对的，such as后的举例defending和scouting之间能有这么长的插入语吗？

假设真是act和sound这两种行为补充修饰defending，那答案B依旧正确吗？还是分词形式？

dreadpower

我觉得such as A,B,andC比较符合表达习惯

    你说的：act和sound这两种行为应该是defending的补充或定义   在意思上确实有那么点

    我的理解是，分词要么修饰前面的名词the entrance，那样理解肯定错
                     要么修饰前面的动作，作伴随动作，状语，但是此句的动作不是defending，defending the entrance,表达一个名词的概念。此句的动作是 have
                     要么表示和defending平行，满对的

    个人意见，大家讨论

excellent

take on different duties such as和take on such different duties as有区别吗？都可以使用吗？

excellent

mindfree的解释：

it depends. in this case, i think both are correct, even though i prefer the first, because "such as" is on "duties". however, you should try to avoid using "such" in front of any adj.

谢谢！

excellent

谢谢dreadpower斑竹的认真解答，很有道理！

ashura

如果都是并列的，那为什么有两个and呢？

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.

应该变成

duties such as defending the entrance, acting as sentinels， sounding a warning at the approach of danger, and scouting outside the cave for new food and roosting sites. 了吧？