A prep SC question: single locusts are quiet creatures

[RonPurewal]

C has a core sentence that says "locusts, they become excited..."
nope. can't have a sentence with 2 subjects. (like trying to write "my friend, she lives in texas.")

[qianruS779]

Thank you very much!!

[RonPurewal]

you're welcome.

[RickyH486]

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

OA is A, but I do not understand why E is wrong. It seems E is more concise than A and does not distort the meaning. Ron, would you please explain to me, thanks!

The original subject is "single locusts".

The second part of the sentence doesn't describe single locusts. The subject of choice E is still "single locusts", so E is nonsense.

The appearance of "locusts" in choice A is NOT "less concise"; it's actually necessary, to specify that we're now discussing the behavior of locusts in general, not single locusts.

Hi master Ron, thanks for pointing out the mistake in E. When I first attempted this problem, between A and E, I eliminated E because I find the parallel structure in A is much better (by the way, always checking parallelisms first is the one of best advices I learned from you!). Do you agree with how I did it? Or did I get this one right by fluke.

[RonPurewal]

there isn't really any parallelism here... what were you interpreting as a parallel structure?

[NicholeL817]

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

OA is A, but I do not understand why E is wrong. It seems E is more concise than A and does not distort the meaning. Ron, would you please explain to me, thanks!

Hi experts,

In B and E, is there a discrepancy that they use when and then in a sentence? Because I think 'when' emphasizes simultaneity while 'then' is a signal marked a sequence in actions.

Looking forward to your guidance!

[Sage Pearce-Higgins]

That's a good characterization of the difference in meaning between 'when' and 'then'. I should add that 'then' can also mean 'at the time mentioned before'. In answer B, we don't need to use both words. The use of 'then' in answer E is suspicious to my ear, but answer E is wrong for other reasons, as Ron has explained above.