使用易燃物品(如乙炔、氢气、油类、天然气、煤气等)的人员,必须熟悉这些物质的()规则。
A.性质及安全存放
B.防爆
C.特性及防火防爆
D.性质及防燃
参考答案:C
_________that Marie was able to set up new branches elsewhere. [ ]
A. So successful her business was
B. So successful was her business
C. So her business was successful
D. So was her successful business
简述合作学习的原则和方法