A:加成→消去→取代
B:消去→加成→水解
C:取代→消去→加成
D:消去→加成→消去
A. It's a nice sweater.
B. It's on the line.
C. No, it isn't. It's on the chair.
D. Yes, I have. The coat is nice.
E. No, I haven't. I've got a new pencil.
读“北美洲沿40°N线剖面图”,回答下面小题。
I have good idea.