prep2-34,2-150

Besides adding complementary flavors to many foods, hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these have a pain-relieving effect like morphine's.

(A) hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these have a pain-relieving effect like morphine's

(B) hot sauces stimulate the release of endorphins in the brain, like exercise, and they have a pain-relieving effect that is like morphine

(C) hot sauces and exercise both stimulate the release of endorphins in the brain, and they have a pain-relieving effect like morphine

(D) the release of endorphins in the brain is stimulated both by hot sauces and exercise, and they have a pain-relieving effect like morphine's

(E) the release of endorphins in the brain is stimulated by hot sauces, just as with exercise, and these have a pain-relieving effect like that of morphine

A

Hydrocarbons, with which fruit flies perfume themselves in species-specific blends, are known to be important in courtship, and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of others.

(A) and apparently this assists flies that taste the hydrocarbons on prospective mates to distinguish their own species from that of

(B) and apparently this assists flies when they taste the hydrocarbons on prospective mates in distinguishing their own species from those of

(C) which apparently assists flies that taste the hydrocarbons on prospective mates in being able to distinguish their own species from

(D) apparently assisting flies to taste the hydrocarbons on prospective mates to distinguish their own species from those of

(E) apparently assisting flies that taste the hydrocarbons on prospective mates in distinguishing their own species from

E

我想问的是,为什么第34题的these可以当主语呢,那150题中的this是不是也可以当主语?

我觉得34题里的these指的是endorphins，因为endorphins在前一句里不是主语，所以后面想说它和吗啡具有同样功效的时候必须另起一句说。而150题里主语都是Hydrocarbons，就没必要另起一句了。况且Hydrocarbons是复数，this assists就不对了。

拙见，望指正！

诶,这个问题真是无人可解拉!!!

these指代的是endorphins

不能用this的原因是this不能指代完整的前句