— Two weeks.
A:How long
B:How often
C:How far
D:How soon
看谁先到家。
①υ(A)=0.5mol•L﹣1•S﹣1②υ(B)=0.3mol•L﹣1•S﹣1
③υ(C)=0.8mol•L﹣1•S﹣1④υ(D)=1mol•L﹣1•S﹣1.