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.
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
OA:b。
答案没问题 。doing ,doing and doing. 但后面还有个and scouting 呢?这句结构岂不成doing ,doing and doing and doing? 这种结构对吗?
Actually, even though logically, a sentence should be in the format A,B,C, D & E [where A= defending B = acting C = Sounding D = Scouting & E = Roosting !!]
However, this is an exception.
If u look at the sentence, they have already mentioned D & E as "and scouting" & "and roosting" in the NON_UNDERLINED part. So taking the GMAC to be right(!), we can parallel this structure!
So in order to parallel that we can have "acting as sentinels" and "sounding" separated by an "AND"
Hope i have made things clearer and not confused u all further ..!!!