单项选择题 Porter"s company has decided to let employees use instant messaging (IM) as an internal communication tool, and she wants to make sure that she"s using it professionally. What should she do?

单项选择题 在化肥中磷矿粉属于（）

单项选择题 溢流进一步发展，钻井液涌出井口的现象称之为井涌。地层流体无控制地涌入井筒喷出转盘面（）米以上的现象称为井喷。