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【简答题】
在外径为 140mm 的蒸气管道外包扎保温材料,以减少热损失。蒸气管外壁温度为 390 °C ,保温层外表面温度不大于 40 °C 。保温材料的 λ 与 t 的关系为 λ =0.1+0.0002 t ( t 的单位为°C, λ 的单位为 W/ ( m· °C ))。若要求每米管长的热损失 Q/L 不大于 450W/m ,试求保温层的厚度以及保温层中温度分布。
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举一反三
【单选题】确诊脑脊液鼻漏的方法为
A.
鼻孔流出无色液体，干燥后不结痂
B.
低头用力、压迫颈静脉流量增加
C.
鼻腔血性液痕迹中心呈红色而周边清澈
D.
液体行葡萄糖定量分析，含量1.7mmol/L以上
E.
以上都不对
【多选题】To realize one's potential and ideals, he or she should:
A.
To be able to put the whole of oneself into one's feelings, one's work, one's beliefs
B.
To follow or submit to our destiny
C.
To seek goodness in life
D.
To achieve eudaimonia, a flourishing of human spirit
【单选题】一斜齿圆柱齿轮传动, 已知法向模数 Mn=4mm,齿数 Z1=20,螺旋角 β=14°
A.
’2”，齿宽 b1＝80，b2＝75mm，则该传动的齿宽系数 φd等于（ ）。
B.
0.852
C.
O.88
D.
0.8
E.
0.907
【单选题】Based one the student's statements, why has she not started the assignment?
A.
Because she has part-time work to do.
B.
Because it was really a big assignment.
C.
Because she hasn't spent time in the library.
D.
Because she was doing work for another course.
【简答题】同时与几个供应商或采购商进行谈判是( )策略A. 4
【单选题】确诊脑脊液鼻漏的方法为
A.
鼻孔流出无色液体，干燥后不结痂
B.
低头用力，压迫颈静脉流量增加
C.
鼻腔血性液体痕迹中心呈红色而周边清澈
D.
液体行葡萄糖定量分析，含量1．7mmol／L以上
E.
以上都不对
【单选题】听力原文：W: A moment, please, sir. You have forgotten the addressee's zip code. M: Oh, I'm sorry. But I don't know that. Is there anywhere I can look it up? Q: Where does this conversation most probably t...
A.
In the post office.
B.
In a department store.
C.
In a supermarket.
D.
In a library.
【单选题】听力原文：M: Can you spare a moment, dear? I want you to listen to this letter. W: Go ahead, then. M: Sir, my wife and I arrived home last night after a holiday arranged by your firm, in Jersey. We stayed ...
A.
Motor vehicles were constantly arriving or departing.
B.
Tasty food.
C.
A comfortable, medium- sized hotel.
D.
Old - fashioned service.
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