泵内发生异音的原因?
参考答案:
泵内发生异音的原因:
油量不足或过多,油质不良;滚珠破裂;皮带过紧,轴承锁紧螺母脱扣。
根据句子意思,用括号中所给单词的适当形式填空。
1. ---Sam usually spends three hours _______(do) his homework every day? What about you, Jack?
--- Two hours.
2. Thank you for _______(help) me clean the garden. I will spend the whole day without your help.
3. ---What's your favourite activities after school?
---I enjoy _________(dance) in the art room.
4. ---Do you know a game ___________ (call) "trick or treat"?
---Yes. Children like to play it at Halloween.
5. ---What do you want to make with the pumpkin?
---We want to make a lantern for Halloween. Can you see the sharp _______ (tooth)?
抗结核杆菌作用弱,但有延缓细菌产生耐药性,多合用给药的是()
A.异烟肼
B.利福平
C.链霉素
D.PAS
E.庆大霉素