某高效净化系统乱流洁净室，其面积为28m2，高为2.5m，有两个顶送_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

某高效净化系统乱流洁净室，其面积为28m²，高为2.5m，有两个顶送风口，3人工作（发尘量G_m为2.7×10⁴粒/m³·min）。新风比为0.2（送风浓度N_s＝1粒/L），室内为30h^-1换气次数，则室内可达到（）含尘浓度。

A．60粒/L

B．70粒/L

C．80粒/L

D．90粒/L

答案

参考答案：B

解析：

由于人员密度，q＝3/28＝0.107人/m²，

得单位容积发生量G_m为2.7×10⁴粒/(m³·min)，因为新风比＝0.2，则

送风浓度N_s＝1粒/L，计算得60粒/L。

如估算或查得＝1.19，则N_s＝71粒/L

单项选择题

省煤器入口循环气体温度为（）℃。

A、170

B、310

C、287

完形填空

阅读下面短文，掌握其大意，然后从21—40题所给的四个选项（A、B、C、D）中，选出最佳选项，并在答题纸上将该选项标号涂黑。
We have been driving in fog all morning, but the fog is lifting now. The little seaside villages are   , one by one. "There is my grandmother's house," I say,      across the bay to a shabby old house.
I am in Nova Scotia on a pilgrimage (朝圣) with Lise, my granddaughter, seeking roots for her, retracing (追溯)      memory for me. Lise was one of the mobile children,      from house to house in childhood. She longs for a sense of      , and so we have come to Nova Scotia where my husband and I were born and where our ancestors      for 200 years.
We soon     by the house and I tell her what it was like here, the memories    back, swift as the tide (潮水).
Suddenly, I long to walk again in the     where I was once so gloriously a child. It still    a member of the family, but has not been lived in for a while. We cannot go into the house, but I can still walk      the rooms in memory. Here, my mother      in her bedroom window and wrote in her diary. I can still see the enthusiastic family      into and out of the house. I could never have enough of being      them. However, that was long after those childhood days. Lise       attentively as I talk and then says, " So this is where I     ; where I belong. "
She has      her roots. To know where I come from is one of the great longings of the human     To be rooted is "to have an origin". We need      origin. Looking backward, we discover what is unique in us; learn the        of "I". We must all go home again—in reality or memory.