辐射散热（）传热介质的作用。
A、不需要
B、需要
C、大部分时需要
D、不能确定
参考答案：A
The building project ______ next year is, I think, not easy ______ in time.
A．being carried out; to complete
B．carried out; to be completed
C．to be carried out; to complete
D．to be carried out; to be completed
有压隧洞
