问题 单项选择题

水温对熟石膏结固时间的影响是

A.水温在0~30℃,随水温增高其结固减慢

B.在50~80℃,水温升高,结固加快

C.在30~50℃,水温对结固时间影响大

D.在80℃以上,结固更快

E.以上都不对

答案

参考答案:E

解析:水温的影响:0~30℃:凝固速度随水温升高而加快。30~50℃:凝固速度随水温升高无明显变化。50~80℃:凝固速度随水温继续升高,反应剧烈,二水硫酸钙晶体被冲碎,减少了结晶中心的形成,反使凝固速度变慢。80℃以上因高温,又再脱水,形成半水硫酸钙而不凝固。

阅读理解

阅读理解

       One day,  as l walked through my office,  I was taught a useful lesson about life. As l opened the

garage door, I saw a large month(飞蛾)on the wall.  1t was a very beautiful moth.  Perhaps because

of the sound of the door opening, the moth flew immediately out.  There is a window on the ceiling(天花板).  The moth tried its best to get out through the window glass.

       I raised the garage door wider to help the moth to escape from the garage.  However, it tried to fly

higher and farther from the door and got trapped(困)in a spider's web. Worrying that the beautiful

moth would become a spider's dinner,  I picked up a broom to help it fight against the spider's web.  

However, it became even more frightened.  After it got away from the web, the moth pumped(扇动)

his wings hard and ran into the glass.  But no matter how hard “tried”, the moth remained in the cage

of the garage.

       I left the garage with the door open.  I thought by simply turning his focus(集中注意)to one side, he CO Lild escape the garage through the door.  Sometimes, people need to choose the right way before applying effort(努力).

根据短文内容,回答下列问题。

1. What was in the garage when the writer opened the door?

                                                                        

2. Did the moth get out through the window glass?

                                                                        

3. Why did the writer pick up a broom to help it fight against the spider's web?

                                                                        

4. How could the moth escape the garage through the door?

                                                                        

5.What do we learn from the passage? 

                                                                        

名词解释