Dear Mr. / Mrs. We are much concerned that your sales in recent months have fallen considerably. At first we thought this might be due to a slack ( 淡季 ) market, but on looking into the matter more closely, we find that the general trend of trade during this period has been upwards. It is possible that you are facing difficulties of which we are not aware. If so, we would like to know what we can do to help. 17. Why does Mr./ Mrs.'s sales have fallen considerably in recent months?