A. 正确 B. 错误
A. 圆柱形 B. 圆锥形 C. 倒圆锥形 D. 长管状
A. 60度 B. 90度 C. 120度 D. 以上皆非
A. The main cause was big power struggle for control of the world. B. It was the worldwide economic crisis. C. It was the military expansion of Japan,and Germany.