1．开门见山，引出话题
I'm writing to you about...which I bought from...
Here are the copies of the guarantee and the receipt.
I am writing to point out some problems with...
2．说明产品的问题
In your advertisement, you claim that...
However, the first time I went.../However, after only one wash, the color had faded.
There are some problems that exist in...
What I want to say is that there is something wrong with...
I was so disappointed when I knew...
