Question

  ---How amazing it is that astronauts are exploring outer space!

----- It’s a challenge, I guess,         man against nature. 

A. of             B. for               C. by              D. about

Answer 1

A

解析:

考查介詞。應(yīng)答句中的I guess是插入語，因此所填介詞與challenge連用，表所屬，用of，選A。