1, used after salutation, means to mention the following. Comrades, let's have a meeting now. It often appears in letters and official documents. Some people often ignore this colon after the address form, which is easy to write as a comma.

2. After the words "say", "think", "yes", "prove", "announce", "for example" and "as follows", it indicates the following tips.

2. Colon is one of the punctuation marks commonly used in writing. ① Half-angle in English is ":",② Full-angle in English is ":",③ Full-angle in Chinese is ":",④ Half-angle in Chinese is ":"

Third, how to use colon and "that is" together needs special explanation. "namely" is equivalent to "just (yes)". Colons can be used after the word "that is" and lead to the following, but not for the word "that is". For example:

1. The quality standard of the finished product book is divided into two grades, namely, qualified products and unqualified products. (Provisions of the General Administration of Press and Publication on Book Quality Management)

2. This kind of human social activity has a series of unique professional characteristics: universality and particularity, theoretical thinking and artistic behavior.

Extended data:

1. There was no colon in the sentence of reading symbols in ancient China. The form and usage of the colon in the current punctuation marks are imported from the west, while the name is ideographic and original. The word "Mao" means "hidden" and "comprehensive". For example, "provoking" and "taking risks" refer to the beginning or introduction of an article or discourse. Lu Xun's statement in "The Wandering Lonely Man" helps to understand the meaning of the word "Mao".

2. Many names 19 19 are used before and after the colon: punctuation, colon, quotation marks, gathering point, narrative point, continuation number, narrative number, knot number, comprehensive number, two points, cool hall, key point, binding point and coren. Hu Shi once suggested the use of ":or" in the form of colon in the article "Sentence Reading and Character Symbols" (19 16), and the name used was "Mao". The former is a western-style colon, and the latter is to change two points of the western-style colon into two Chinese-style sharp points.

3. The punctuation marks suggested by Qian in the article "Sentence Reading Symbols" (19 18) are "Mao or Jie". The word "knot" obviously refers to summing up the above. The form and name of the colon were formally determined in 19 19's Proposal on Promulgating a New Punctuation Law.

References:

Baidu Encyclopedia-Colon