The letter ended on a cheerful note.

这封信以乐观的口气收尾。

《新英汉大辞典》

When his professor found the message, he returned the paper to the student with a cheerful note as a response. It read: "God gets an a; you get an F."

他的教授看到了这句话，就把试卷发回给他，并附上一个欣然的回答：“上帝得了个‘优’，你得了个‘差’。”

youdao

May this Christmas be bright and cheerful and may the New Year begin on a prosperous note!

愿圣诞节快乐美好，并愿您在新的一年中有一个美好的开始！

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Speaking on Broadcasting House Aitken - a former Conservative cabinet minister - said he sent Huhne a book of psalms, along with a "cheerful" note, and received a "nice letter back".

BBC: Chris Huhne and Jonathan Aitken exchange letters