乙炔气瓶、氧气瓶、焊枪三者间距离各自都应保持安全距离，且应远离敞开的（）和电线
参考答案：电源开关
The belief that the children of working mothers usually suffer is by most scientists.
A．rejected
B．refused
C．resisted
D．reduced
种质资源的保存方式有哪几种？分别阐述各自特地。
