我寫這封信是為了投訴……
點睛本句型是典型的投訴信件的開頭。本句型中，complain about sth. 是固定搭配，表示“抱怨某事物”，about不能替換為其他介詞。
句型拓展I am writing to express my dissatisfaction with your service. 我寫這封信是想表達我對于你們服務(wù)的不滿。
I beg to call your attention to the fact that your service is very dissatisfactory. 我想請你們注意，你們的服務(wù)非常令人不滿。
I wish to refer you to an incident which occurred last Friday, calling for some remedial action. 我想告訴你，上周五發(fā)生的事急需采取補救措施。
I very much regret to have to inform you your service is very dissatisfactory. 很抱歉地告訴你，你們的服務(wù)非常令人不滿。
I am totally disappointed to find that your service is very dissatisfactory. 你們的服務(wù)非常令人不滿，對此我很失望。
