请教两个语法

慕渊

39: GWD-29-Q26

In his experiments with gravity, Isaac Newton showed how the motion of each planet in the solar system results from the combined gravitational pull of the Sun and of all the other planets, each contributing according to their mass and distance from the others.

A.of all the other planets, each contributing according to their

B.of all the other planets, with each of them contributing according to their

C.all the other planets, each of which contributing according to its

D.all the other planets, each contributing according to its

E.all the other planets, each of which contribute according to their

答案D，我选A，不是介词应该尽量补出吗？
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40: GWD-29-Q29

Most of Portugal’s 250,000 university students boycotted classes in a one-day strike to protest a law that requires them to contribute $330 a

year toward the cost of higher education, previously paying $7 per year.

A.year toward the cost of higher education, previously paying $7 per year

B.year toward the cost of higher education, for which was previously paid $7 per year

C.year, compared to the previously $7 per year, toward the cost of higher education

D.year toward the cost of higher education, instead of the $7 per year required previously

E.year as opposed to the $7 per year required previously for the cost of higher education
答案D，我选C。觉得D的in stead of 前后对称得不好……

dodomerry

39：A项的of 可以省略，而且each后面应该用its 而不是their.
40: C项逗号后的compared to ，有歧义，修饰year，不太合理。相比之下D项的instead of 后接的$7 per year 是名词与前面的$330  a year 对称。
open to discussion~