下列不属于电磁炉优点的是（）

A、升温快，热效率高

B、无明火，无烟尘，无有害气体

C、体积大，安全性差

D、外观优美，对周围环境不产生辐射

The news _____ the prime minister will pay a visit to our school next week has not yet being confirmed.

A．when

B．whether

C．that

D．Why