It’s reported that Nest Chat allows users to block others when they want to avoid _______.

A．to be disturbed

B．to disturb

C．being disturbed

D．disturbing

在测量氨气压力时，必须使用（）材质弹簧管的压力表。

A.磷青铜

B.不生锈

C.合金钢

D.碳钢