文中共有10处语言错误，要求你在错误的地方增加、删除或修改某个单词。

增加：在缺词处加出加一个漏字（^），并在其下面写上该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意： 1. 每处错误及其修改均仅限一词；

2．只允许修改10处，多者(从第11处起)不计分。

Dear manager,

I am a student of senior three. Last Sunday I went to shopping in your supermarket. Your service was very good, and I felt worried because there are some problem there. First, the windows of the walls are tightly closed so the fresh air cannot move in, that can easily lead to all kinds illnesses. Second, there is large quantities of goods on the third floor, but they are in a mess. It is not easy to find which I want to buy. In addition, the EXIT signs can’t be see easily, so if something terribly happened, it would be difficult for people to get in quickly. I hope you can make some improvements.

正常运行中，空预器漏风的危害有（）。

A、增加了引风机的排烟量，也增加了引风机的电耗

B、送风机部分风量走短路进入烟道，使得进入炉膛的空气量减少，严重时会造成燃烧空气量不足，锅炉运行出力下降

C、送风机电耗上升

D、降低了空预器传热效率