请教大全659题（og 3）

看了各位nn的帖子。大体归纳三种思路：

A:defending,acting and sounding,scouting 这三个并列

B:defending,sounding,scouting 并列，acting修饰defending

C:defending，scouting并列，acting and sounding修饰defending

根据gemj牛牛的理解，因为defending本来就是状语，所以BC错

根据蓝夕叶子牛牛的理解，acting and sounding是对defending的补充。

若从句意理解：哨兵应defending entrance，并且sounding approach of danger warning，acting and sounding应为对defending的补充。

并且entrance也与outside the cave对应。符合蓝夕叶子牛牛的观点

OG解释为：acting and sounding should parallel to defending and scouting；

 observes the parallel­ism required among and within the three main verb phrases. 仔细体会among and within the three main verb phrases 。解释为三个动词短语平行。若为2个平行，among应改为between，所以 ETS的思路与gemj牛牛相同。

所以大家还是按照ETS思路理解吧~~~

如有不对请指正！！！