I am trying to write a letter in which I ask the supplier whom we deal with
to certify that the cars and drivers of their company will comply with LRS
(life saving rules) what are the forms of a letter you suggest
Thanks in advance
Welcome to the forum, hanygergiss.
What are you looking for? If your question is about format, you should look here. Business Letter Writing Basics
If you have a question about English, I would suggest that you write the letter and post it here. Someone will comment on it. From the way you have framed your question, it seems to me that you have a good command of English.