下列计算正确的是[ ]
A．ax+y=axy
B．﹣5ab+5ba=0
C．3a2+a=4a3
D．5m3﹣2m2=3m
答案：B
三讲
--How did ____ feel to run 3000 meters at the sports meet?
--Terrible! Especially when I saw I was left so far _____ by the others.
A．that; alone
B．it; alone
C．that; behind
D．it; behind
