压缩机组冷启动时,当速度升到()rpm时,必须保持该速度预热20分钟左右。
A、500
B、1000
C、1500
D、2000
参考答案:A
If you don't know how to spell a new word, you'd better ______. [ ]
A.look up a dictionary
B.look up an dictionary
C.look it up in an dictionary
D.look it up in a dictionary
"主治节",是哪个脏腑的生理功能
A.肝
B.心
C.脾
D.肺
E.肾