—I don't know. Maybe the traffic is heavy(交通拥挤).
A:this
B:that
C:it
D:he
把一张矩形纸片(矩形ABCD)按如图方式折叠,使顶点B和点D重合,折痕为EF.
不同物体的传热____不一样,容易传热的物体叫____,不容易传热的物体叫____。