请教gwd19里的几道语法题

21. GWD28-Q21:

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.

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

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

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

4. placing them with others of their species,

5. placed with others of their species, then

   Answer: A 我选E因为分词〉从句，关于代词也可以前句的主语得来。

Unlike the body’s inflammatory response to cuts and sprains, with widespread swelling and stiffness immobilizing the injured area until it heals, the body’s response to sunburn is more localized and resulting in a distinct line dividing affected and unaffected areas of the skin.

1. with widespread swelling and stiffness immobilizing the injured area until it heals, the body’s response to sunburn is more localized and resulting

2. where the injured area is immobilized with widespread swelling and stiffness until it has healed, sunburn generates a more localized response in the body, which results instead

3. with the injured area immobilized by means of widespread swelling and stiffness until healing, sunburn generates a more localized response in the body, one resulting

4. in which widespread swelling and stiffness immobilize the injured area until it has healed, the body’s more localized response to sunburn results

5. in which widespread swelling and stiffness immobilize the injured area until healing, instead, the body’s more localized response to sunburn results

   Answer: D 我选A因为和分词的逻辑主语一致。

请指教