A:v(A)=0.5 mol•L﹣1•s﹣1
B:v(B)=0.3 mol•L﹣1•s﹣1
C:v(C)=0.8 mol•L﹣1•s﹣1
D:v(D)=1.6 mol•L﹣1•min﹣1
He was told ____ (drive) carefully.
若x>y,则ax>ay.那么一定有( ).