请对图中的6项知识进行讲解---**Section: 知识解读 (Knowledge Interpretation)**
**Section: 回顾 (Review)**
**1. 代数式 (Algebraic Expressions)**
(1) 代数式的概念: 用______把数或表示数的字母连接起来的式子. 单独的一个______或______也是代数式.
(1) Concept of Algebraic Expressions: An expression formed by connecting numbers or letters representing numbers with ______. A single ______ or ______ is also an algebraic expression.
(2) 代数式的书写:
(2) Writing Algebraic Expressions:
① 数字与字母相乘，数字在前，字母在后，乘号换“·”或省略；
① When numbers and letters are multiplied, the number comes first, then the letter, and the multiplication sign is replaced by "·" or omitted;
② 相同字母相乘时，写成乘方的形式；
② When identical letters are multiplied, write them in the form of powers;
③ 除号改为分数线；
③ Division sign is changed to a fraction bar;
④ 数字为1或-1时，数字“1”要省略；
④ When the number is 1 or -1, the number "1" should be omitted;
⑤ 带分数改为假分数；
⑤ Mixed numbers are changed to improper fractions;
⑥ 有单位时，乘除运算直接加，加减运算添括号.
⑥ When there are units, multiplication and division operations directly add, and addition and subtraction operations add parentheses.
**2. 单项式 (Monomial)**
(1) 单项式的概念: 数或字母的______ . 单独的一个______或一个______也是单项式.
(1) Concept of Monomial: The ______ of numbers or letters. A single ______ or a single ______ is also a monomial.
(2) 单项式的系数: 单项式中的______因数.
(2) Coefficient of a Monomial: The ______ factor in a monomial.
(3) 单项式的次数: 所有______的指数的_______.
(3) Degree of a Monomial: The ______ of the exponents of all ______.
**3. 多项式 (Polynomial)**
(1) 多项式的概念: 几个______的和. 其中，每个单项式叫作多项式的______ . 不含字母______的项叫作______项.
(1) Concept of Polynomial: The sum of several ______. Among them, each monomial is called a ______ of the polynomial. A term that does not contain letters is called a ______ term.
(2) 多项式的项数: 一个多项式包含的______的个数.
(2) Number of terms in a Polynomial: The number of ______ contained in a polynomial.
(3) 多项式的次数: 多项式里，次数______项的次数.
(3) Degree of a Polynomial: The degree of the term with the ______ degree in the polynomial.
**4. 整式 (Entire Expression)**
4. 整式: ______与______统称整式.
4. Entire Expression: ______ and ______ are collectively referred to as entire expressions.
**5. 同类项的概念 (Concept of Like Terms)**
5. 同类项的概念: 所含______相同，并且相同字母的______也相同的项.
5. Concept of Like Terms: Terms that have the same ______ and the same ______ of the same letters.
**6. 合并同类项 (Combining Like Terms)**
(1) 合并同类项的概念: 把多项式中的______合并成一项.
(1) Concept of Combining Like Terms: Combining ______ in a polynomial into one term.
(2) 合并同类项的法则: ①系数______；②字母及其指数______ .
(2) Rules for Combining Like Terms: ① Coefficients ______; ② Letters and their exponents ______.