Comma it is preceded by a semicolon and followed by a comma. Using commas to offset certain adverbs is optional, including "then", "so", "yet", "instead", and "too" (meaning "also"). Commas are often used to enclose parenthetical words and phrases within a sentence (i.e., information that is not essential to the meaning of the sentence). Such phrases are both preceded and followed by a comma, unless that would result in a doubling of punctuation marks or the parenthetical is at the start or end of the sentence. The following are examples of types of parenthetical phrases: A comma is used to separate
That that is is that that is not is not is that it it is was noted in "Brewer's Dictionary of Phrase and Fable". This phrase appeared in the 1968 American movie "Charly", written to demonstrate punctuation to the main character Charly's teacher, in a scene to demonstrate that the surgical operation to make the character smarter had succeeded. That that is is that that is not is not is that it it is That that is is that that is not is not is that it it is is an English word sequence demonstrating syntactic ambiguity. It is used as an example illustrating the importance of proper punctuation. The sequence can be understood as