非洲的沙漠面积约占整个非洲面积的多少？
参考答案：
1/3
风砂轮是用压缩空气驱动电动机带动砂轮转动实现对加工件表面清理的。其设备简单，使用方便，适用于小面积和焊缝的清理。( )
You will have an idea of what a hard life the working people________at that time after you read the book. [ ]
A. enjoyed
B. shared
C. managed
D. lived
