Trả lời:

Dear sir/madam,

I would suggest that the problem of many people litter trash into the lake which behind my house these days. This makes the water in the lake would be more dirty, more stinky and sometimes we don't have enough clean water to use. It also make our life in the house feel very uncomfortable and I would like to stop this problem right now. I suggest you telling or calling upon them stop littering trash and raising their awareness.

I look forward to hearing from you and seeing good response from you. 

Yours faithfully,

(Your name)

 ~HỌC TỐT~

Dear ..........
I am writing to you about the problem of fish catching in the lake behind my house.
These days, there have been a lot of people coming here to catch the fish. The problem is that they use electricity to catch fish. This way, I think, is very dangerous. Right now, if you come here, you realize a lot of fish, small or big, are floating on the surface of the lake. Not only fish but even some other animals such as frogs, toads, and small birds are killed by electric shock waves as well.
I would suggest that you should prohibit people from catching fish here. If not, I am afraid all of the fish in the lake are not going to exist in the near future.
I look forward to seeing your resolution to this important matter.
Yours sincerely