You should also use an appropriate formal ending phrase, such as 'Yours sincerely' when you know the reader, or 'Yours faithfully' when you don't.

你还应该使用一个适当、正式的结尾短语，比如当你了解阅读者的时候使用“你真诚的”，当你不了解读者的时候使用“你忠实的”。

I always sign off a formal letter, is " Yours faithfully" .

我总是在一封正式的信上签字，是“你忠实的”。

Because if it's a formal letter then you start with: " Dear Sir" or " Madam" , and you end with: " Yours faithfully" .

因为如果这是一封正式的信件，那么您会以“尊敬的先生”或“女士”开头，并以“您忠实的”结尾。

Darwin replied, “Dear Sir, I am sorry to have to inform you that I do not believe in the Bible as a divine revelation and therefore not in Jesus Christ as the Son of God. Yours faithfully”.

“尊敬的先生，我很抱歉地告诉您，我不相信圣经是上帝的启示，因此不相信耶稣·基督是上帝之子。”