为什么要控制航煤的比重（密度）？_爱下问搜题

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问题问答题论述题

为什么要控制航煤的比重（密度）？

答案

参考答案：

因为飞机油箱的体积有限，燃料密度大，则其体积发热值也较大，在同样油箱体积下，飞机的续航时间和续航里程增加，可提高工作效率，降低载运货物的运输费用。

完形填空

The story was a true one and still moved me deeply. Thirty years ago，I got to know a   36 lady named Rose. She had no kids and lived alone.     37   I went to visit her, I always took Rose some coffee and food. One day she said she    38    me to have hunch.
We walked from my work place to a little restaurant on David Street.    39    the way, I began to worry: I knew that she had no money, but if I offered(提供) to    40   the lunch，I was afraid I would hurt her.
There were many people in the    41    and all of them were happy. Rose told me to sit and drink coffee by the window. Then she went to    42  in the kitchen. After about 20 minutes, she came out and sat with me. She just paid for one meal and we started to   43  the delicious food together. She told    44    that the restaurant let people work for a meal if they had no money, or would give them a free meal if they were not able to work. To my surprise, she also explained that the workers who were working there were all    45   .
I     46    remember the beautiful afternoon I shared with Rose.    47    we had a meal together only once, it was paid by Rose's work. The weather was    48    and bright, and everyone's smile was warm and bright as well.
I’m still thinking that life cannot be easy to us, but we can still do     49    for our friends and neighbors. The world will be     50    if everybody would like to share happiness with others. It will never be dark if there is a light in everyone's heart.

A．will invite

B．was inviting

C．is inviting

多项选择题

根据《中国移动900/1800MHzTDMA数字蜂窝移动通信无线网工程验收规范》，设备通电前检查（）。

A.无线设备安装

B.设备模块开关设置

C.射频电缆

D.电源引入