A:2
B:3
C:4
D:6
木匠在木料上画线,先确定两个点的位置,就能把线画得很准确,其依据是( )
— It's dangerous to swim here. Look at the sign.
— Oh, I notice it. Thanks for telling me.
一块梯形菜地的上底是140m,下底是160米.高是50m,平均每平方米收白菜0.48kg,这块菜地收白菜____吨。