For some time the expert __________ people of the health risks caused by passive smoking. He     says he won’t stop until all the smokers around him decide to quit smoking.

A．is warned

B．is warning

C．has been warning

D．has been warned

在水利水电工程等别划分时，Ⅳ、Ⅴ等工程的工程规模属于（）工程。

A.大型

B.中型

C.小型

D.不确定