time went by, small clever animals covered the earth and have become the most important a

time went by, small clever animals covered the earth and have become the most important animals on the planet.
A. With
B. As
C. Because
D. During

A. With(答案→)B. AsC. BecauseD. During解析：本题考查连词。With介词，随着，接名词； As由于，随着，接从句；Because 因为，接从句；During在期间。句意：随着时间流逝，聪明的小型动物覆盖了地球并成为这个星球上最重要的动物。as在句中是“随着……”的意思，故选B。

感谢回答，我学习了