密封涂料的作用是什么？

阅读理解。

                                                                 Accident report

       Daisy witnessed (目睹) a road accident. She went to the police station with her mother to make a

  statement.This is what she said.

       At about 8 :30 A.M. I was walking along Ocean Road towards the school. A boy on a bike passed

  me, going in the same direction. He was riding his bike properly and keeping close to the sidewalk. The

  street was empty.

       Suddenly a car came along the street. It passecl me, then as it passed the boy on the bike it hit him.

  He fell off his bike onto the road. The car did not stop, but continued on its way. I believe the driver

  knew he'd hit the boy because I saw him look back.

       The car was quite old. It was red. I think it was a Ford Escort. I did not get its number because the

  license plate was covered with dirt. The driver was a man. He had long hair. He wasn't an old man but I

  can't guess his age.

       I ran to the boy. He was badly hurt so I ran to a nearby shop and called the paramedics. They

  amvecl with a police car. I told a police officer what I had seen. She asked me to make this statement at

  the police station.

                                                                                                                                        Signed

                                                                                                                                    Daisy Jones          

1. Where did the accident happen?

A. At Daisy's school.

B. On Ocean Road.

C. Outside Daisy's house.

D. Outside the police station.

2. When did Daisy first see the boy on the bike?

A. When he was hit by a car.

B. When she got to school.

C. When he passed her on his bike.

D. When a car came along the street.

3. Why couldn't Daisy give the police the car's number?

A. Because there was no number at all on the license plate.

B. Because the car drove off too quickly.

C. Because there was something dirty on the license plate.

D. Because Ford Escort had no license plate.

交片是民国初所设置的在中央政府内部使用的特殊（）文种。

在Windows的资源管理器窗口中，为了将选定的硬盘上的文件或文件夹复制到软盘，应进行的操作是______。

A．先将它们删除并放入“回收站”，再从“回收站”中恢复

B．右击，并选择“发送到”下的“3.5英寸软驱（A）”

C．先用执行“剪切”命令，再执行“粘贴”命令

D．用鼠标右键将它们从硬盘拖动到软盘，并从快捷菜单中选择“移动到当前位置”

使用蓄电池放电测试仪对一组500AH蓄电池组进行放电测试，若以3小时率放电，则需设置放电电流为（）。

A.125A

B.200A

C.150A

D.100A

已知A，B，C都是三水平因素，A×B，B×C不可忽视。若希望试验次数尽可能少一些，实验设计时最好选择_________

A．拉丁方设计
B．正交设计
C．析因设计
D．交叉设计
E．配对设计