(2)If we learn about first aid，we can help someone who has had an accident.

2．用定语从句改写第三句。

Place the area which is affected under cold running water，but don't apply cold water for too long a time.

3．用非限制性定语从句改写第四句。

The first aid course is very interesting and useful，which gives us information about many situations.

　　用适当的过渡词语，把以上词汇和句式，再加上联想内容，组成一篇100词左右的英语短文。

参考范文

Dear John，

　　I am glad to receive your letter，and now I'll tell you something about the first aid course in our school and some suggestions about first degree burns.

　　If we learn about first aid，we can help someone who has had an accident，and can even save someone's life one day.

　　The suggestions about first degree burns are as follows.Cool the burned area at once.Place the affected area under cold running water，but don't apply cold water for too long a time.You'd better go to hospital if the affected area is still painful.

　　The first aid course is very interesting and useful，which gives us information about many situations，and also gives us a chance to practise first aid treatment.Would you like to come here to study again? We are all looking forward to it.

　　Best wishes!

Yours，

Li Hua