A:沙尘暴
B:温室效应
C:酸雨
D:“三北”防护林
阅读北半球某地“气温曲线和降水量柱状图”回答:
读“以极点为中心的投影图”完成下题
——Mr Li, I can't understand everything in class.——Don't worry! I'll _____ _ the main points at the end.