你可能感興趣的試題

A gate valve installed in a pipeline should be （）.

A.used in either the fully dosed or fully opened position
B.installed with the stem down
C.used for steam service only
D.used to throttle or regulate the flow of liquid

單項(xiàng)選擇題

Which of the following modes of heat transfer does NOT require any physical contact between a warmer and a cooler substance?（）

A.Radiation
B.Conduction
C.Natural convection
D.All of the above