time went by, small clever animals covered the earth and have bee the most important animals on the planet.
A. With
B. As
C. Because
D. During
网友回答
A. With
(答案→)B. As
C. Because
D. 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。