题目：
A compressor should never be stopped （）.
A.without first cooling it
B.without first heating it
C.without first unloading it
D.without first loading it
答案：
参考答案：C
A compressor should never be stopped （）.
A.without first cooling it
B.without first heating it
C.without first unloading it
D.without first loading it
参考答案：C
