问题 问答题 简答题

在开停期间减二泵为什么容易出现抽空现象?

答案

参考答案:

在开工停工期间由于系统内主要是开工溶剂,因开工溶剂初馏点较低在减二正常抽出温度下易发生抽空现象,当投煤经过6小时后,系统内液化生成油增多,减二泵会逐渐运转正常。

写作题
书面表达。
      假设你是李明,你的澳大利亚朋友Dick得知你校正在推行素质教育,你现在的周末生活与过去相比发生了很大变化。请你根据下表提供的信息,用英语写一封信告诉他发生的变化。
过去 (in the past)
现在 (now)
白天  6点超床、上课 (上午4节,下午4节)
(get up, have four classes)
不必去上学,可以做自己喜欢的事 (举例)
(don't have to go to school, can do what I like to do)
晚上做家庭作业或复习功课
(do homework, go over the lessons)
可以看电视、上网、读课外书等 (for example,
watch TV, surf the Internet, do some reading.)
就寝 10:30 (got to bed at…)9:30 (go to bed at…)
注意:1. 词数:约100词; 
          2. 信的开头已写好,不计入总词数。
Dear Dick,
        I am glad to hear from you again. My life at weekends has changed a lot since last year…                       
                                                                                                                                                              
                                                                                                                                                              
                                                                                                                                                              
 
      Best wishes. 
                                                                                                                                  Your friend,
                                                                                                                                   Li Ming   
单项选择题