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【单选题】
Breakfast is of great importance( 重要性 ). It's one of the most important meals of the day. To build a strong body and keep fit, everyone should always eat a good breakfast. Eating the right food is necessary for good health. We may have eggs, bread, milk for our breakfast. Many fathers and mothers don't get their children to eat breakfast because they don't have breakfast themselves. It's bad for their health. Without breakfast, children may not grow as fast as they could, and may not study, play as well at school in the morning as they could. They can fall ill easily, and when they're ill, it may take them longer to recover ( 恢复 )than those children with good eating habits. Without food, the body will stop working. Nobody can live without food. 3. In this passage the writer wants to tell us______.
A.
how to eat breakfast
B.
that parents may not have breakfast
C.
that people can't work without breakfast
D.
the importance of breakfast
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参考答案:
举一反三
【简答题】一周两到三次
【单选题】初发型心绞痛是指初次发生劳累性心绞痛时间未到( )
A.
一周
B.
两周
C.
三周
D.
一月
E.
两月
【单选题】设曲线 C 是右半个圆,定义为: ,则 = ( )
A.
0
B.
2/3
C.
2
D.
1
【简答题】一周两到三次
【单选题】与抗体产生有关的细胞是
A.
B细胞
B.
嗜酸性粒细胞
C.
嗜碱性粒细胞
D.
肥大细胞
E.
NK细胞
【单选题】用离心泵将密闭容器中的有机液体送出,容器内液面上方的绝压为85kPa。在操作温度下液体的密度为850kg/m3,饱和蒸汽压为72、 12kPa。吸入管路的压头损失为1、5m,所选泵的允许汽蚀余量为3、0m。现拟将泵安装在液面以下2、5m处,问该泵能否正常操作?( )
A.
Hg ≤3、5m
B.
Hg ≥3、5m
C.
Hg ≤2、5m
D.
Hg≥2、5m [参考答案]泵的最大允许安装高度 Hg 允许=(Po -Pv )/ρg -Δh -∑Hf =[(85-72、12)×1000]/850×9、81-30-1、5=-2、96m 而实际安装高度H g 实=- 2、5m>H g 允,说明此泵安装不当,泵不能正常操作,会发生汽蚀现象。为保证泵的正常操作,泵应至少安装在液面下方3、5m或更低。Hg ≤3、5m
【简答题】用离心泵将密闭容器中的有机液体送出,容器内液面上方的绝压为85kPa。在操作温度下液体的密度为850kg/m3,饱和蒸汽压为72.12kPa。吸入管路的压头损失为1.5m,所选泵的允许汽蚀余量为3.0m。现拟将泵安装在液面以下2.5m处,问该泵能否正常操作?
【单选题】与抗体产生有关的细胞是
A.
红细胞
B.
粒细胞
C.
Tc 细胞
D.
巨噬细胞
E.
B 细胞
【简答题】用离心泵将密闭容器中的有机液体送出,容器内液面上方的绝压为85kPa。在操作温度下液体的密度为850【图片】,饱和蒸汽压为72.12kPa。吸入管路的压头损失为1.5m,所选泵的允许汽蚀余量为3.0m。现拟将泵安装在液面以下2.5m处,该泵( )正常操作。(能、不能)
【单选题】急性短暂性精神障碍可在( )内完全恢复。
A.
两周
B.
三个月到一年
C.
两个月到半年
D.
两个月到三个月
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