注册水利工程造价工程师持证上岗，必须且只能在（）担任编制、校核、审核和咨询的相应文件上签字盖章。
A.下级
B.上级
C.自己
D.合作者
参考答案：C
There is a possibility that he will a door to universities closed, for he pays no attention to his study.
A．end up with
B．put up with
C．come up with
D．catch up with
安装旋塞阀、球阀、闸阀时，允许介质从任意一端流入或流出
