阀门安装时，应注意阀体上箭头方向，它应与（）一致。
参考答案：介质流动方向
.— Can I use the telephone on the table,sir?
—Under no circumstances____to use the telephone in the office for personal affairs.
A．anyone is allowed
B．nobody is allowed
C．is anyone allowed
D．is nobody allowed
终生浮游的海洋原生动物有哪些种类？
