机械密封中，动环是与轴一起旋转的环形零件，（）是固定在端盖或密封腔上的环形零件。
参考答案：静环
(2013·太原一模)—Who is standing over there?
—It must be ________ from an express company.
A．everybody
B．somebody
C．nobody
D．anybody
确定型决策
