In a polynomial, there are two or more terms, and every two terms are connected by addition or subtraction.

Each term of a polynomial consists of one or more letters (including numbers), and each letter is connected by a multiplication symbol, which is called a term. For example:

Ab-cd (with two items) 2ab+b-a (with three items) -a? +4ab+3b？ -a？ B (there are four projects)