Z41H-16P代表的是（）.
A.焊接闸阀
B.法兰连接闸阀
C.焊接截止阀
D.法兰连接截止阀
参考答案：B
He knew that cholera would never be controlled _____ its cause was found.
A．till
B．still
C．until
D．kill
情况特殊时，可超负荷使用起重机与工具和索具。
