高的需求交叉弹性表明高的产品差异和低的可替代性。
参考答案：错
—Would you mind my little sister while I am away?
—Of course not. [ ]
A. looking for
B. looking at
C. looking after
D. looking forward to
加热炉热电偶保护管末端超过炉管的长度应为（）mm
A.50～100
B.10～20
C.40～50
D.100～200
