单机试运时，合格的机械密封泄漏量的标准是不大于（）滴/分。

A、5

B、10

C、15

D、20

Why are the prices of mobile telephone services lower in China’s eastern coastal region

A．The average disposable income is lower in the region.

B．The GDP is higher in the region.

C．The costs of operators are lower due to a greater number of users of mobile phone services in the region.

D．The operators compete with each other in order to win over subscribers.