GWD28-Q21 有点疑问

alexnerohero

According to entomologists, single locusts are quiet creatures, but when locusts are placed with others of their species, they become excited, change color, vibrate, and even hum.



A.when locusts are placed with others of their species,

B.when placing them with others of their species, then

C.locusts, when placed with others of their species,

D.placing them with others of their species,

E.placed with others of their species, then
1   对于 选项 A 和选项C ,,,,,辨别不太清楚《，，，，，，，C   感觉更加符合ETS 的答案习惯吧~~~~~有点同谓语的感觉~~~~~~~~~~~~~~~
2   最好的答案我觉的是  when placed with others of their spieces, they .....    没这选项哎   因为 but l连接2 个完整的句子 而且这里主语都是 locusts,,, 所以能省略吧，，，，，
以上个人意见，，，，，求指导

eshopaholic

我选A

大家讨论

gmat928

A.when locusts are placed with others of their species,
正确

B.when placing them with others of their species, then
placing的逻辑主语不能是后面的they(locusts)  

C.locusts, when placed with others of their species,
locusts和后面的主语they重复

D.placing them with others of their species,
placing的逻辑主语不能是后面的they(locusts)  

E.placed with others of their species, then
their没有指代对象

reneegreen

then在这里是不是可有可无的呢

sisichen666

then好像只有和and连用时：and then的情况下会有并列连词的作用，单独来讲，then无什么作用吧。。。。。。。。。。。