壳管干式蒸发器，适用于（）制冷剂。
A、R502
B、R717
C、R22
D、R13
参考答案：C
When the young man came back, tired, he just forgot to turn on the radio and ________ missed
the program.
A. anyhow
B. thus
C. however
D. somewhat
“合同协议号”栏应填（）。
A．LC326098000049
B．8EOW3230167JP
C．COSU71882006615
D．1106919004
