压缩机中的冷冻油必须适应制冷系统的特殊要求,能够()。
A.耐高温而不凝固
B.乃高温而不汽化
C.耐低温而不汽化
D.耐低温而不凝固
参考答案:D
肺痈病人咳痰的特点是()
A.痰白清稀或有灰白点
B.痰黄黏稠有块
C.痰少而黏,难咯
D.脓血痰味腥臭
E.痰白滑量多,易咯
No one asked for me while I was out, ___?
A.didn't he
B.did they
C.did it
D.do they