Book: A letter from home is a letter from home, and a personal letter is a personal letter.
Letter: A memo is a letter, and an official letter is an official letter.
Zagreb: Great Zagreb is an important letter, and a gift letter is a gift letter.
Jane: A letter is a letter, but Jane believes it.
Note: Even if the note is a letter, brocade note and fancy note are good names for a letter.
Letters: namely letters and notes. In ancient times, a foot-long piece of wood was often used to write letters.
Ruler rope: silk book. Write a letter with a foot-long white silk.
Carp and swan goose: both originated from ancient China allusions, and gradually evolved into synonymous letters.