压力管道选用的伴热介质即热载体有（）
A、热水
B、水蒸汽
C、联苯
D、联苯醚
参考答案：A, B, C, D
4的算术平方根是（ ）。
---Could you please help me check what's wrong?
---Sorry, I don't have much _______of the computer.
A．introduction
B．development
C．knowledge
D．information
