硬质玻璃贮样容器宜于贮存有机物水样、生物水样及六价铬、硫化物、（）等项目的水样。
A、氨
B、钾
C、钠
D、钙
参考答案：A
_________ no doubt that a green campus plays an important role in the growth of students, both physically and mentally.
A．It is
B．There has
C．There is
D．It has
进出口货物收发货人在报关注册登记后取得报关权，可以接受他人委托代理其办理报关纳税手续。( )
