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．a(chǎn)bout

Answer 1

A

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