OK. Here is the original question:
Quote:Why is it ok to use "The room contained the following: a chair, table, a rug and a sofa." When the sentence before the colon isn't complete?
The questioner refers to the 'sentence before the colon'. What is before the colon is not a 'sentence', it is an introductory phrase. A sentence starts with a capital letter, and is a group of words, usually containing a verb, that expresses a complete thought in the form of a statement, question, instruction, or exclamation and starts with a capital letter when written, and ends with a period, a question mark or exclamation mark. If you took the introductory phrase ""The room contained the following" and stuck a period on the end, you would have something which looked like a sentence but which would be incomplete.