化学品吊装作业要求？
参考答案：
在吊装化学品时除常规吊装的作业要求以外，作业前应检查容器有无损坏和泄漏，人员必须穿戴防护服和橡胶手套。
请简述磁选的概念？
All the students at school are required to ____ lectures by the experts on howto save themselves when accidents occur, such as fires, a gas leak and so on.
A．join in
B．take part in
C．attend
D．participate in
