下列自救措施中不合理的是（）

下面是阳光小学四、五年级为希望小学捐书情况统计图，根据图片回答下列问题：

1. （1）四、五年级共捐书（____   ）本。
   
2. （2）（____   ）年级捐书最多。
   
3. （3）四、五年级捐的（____   ）书同样多。
   
4. 

Dear David,

    I'm very glad you are arriving in my city at 3:00 p.m. this Sunday. Now let me tell you the way to the Blue Sky Restaurant. I'll meet you there. Take a taxi from the bus station and go down New Bridge Avenue. Go across the big bridge. When you see a bank, turn right and go through Bank Street. You'll pass three one-way avenues: Sixth Avenue, Seventh Avenue and Eighth Avenue. When you see a big McDonald's, turn left. Then go along Green Avenue until（直到）you see New Park. Turn left and go down Center Street. The Blue Sky Restaurant is on your right.

    I hope you have a good trip.

Yours,

Larry

电视机、电脑的荧光屏表面，使用一段时间后，会有很多灰尘，这主要是因为（　　）