求助:两道难题

Gas hydrates, chemical compounds of water and natural gas, are increasingly being studied for their potential to be huge reservoirs of energy, possibly causing sea floor instability, and significant contributors to global warming.

A.      to be huge reservoirs of energy, possibly causing sea floor instability, and

B.      to be huge reservoirs of energy, possibly causing sea floor instability, and even as

C.      as huge reservoirs of energy, possibly causing sea floor instability, and

D.     as huge reservoirs of energy, and the possible cause of sea floor instability,

E.      as huge reservoirs of energy, as possible caused of sea floor instability, and even as

Most of Portugal’s 250000 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

1.A or E,but i prefer E

2.pick for A

1.A

2.D.该题的B值得考虑。但是，contribute和 paid 不相配。

open to discuss