1, the concept of complex fraction is abstract, which is easy to confuse and misunderstand students, while the concepts with fraction and mixed number are more intuitive and more in line with students' mathematical cognitive ability.

2. The frequency of complex fraction in practical problems is low, and the operation of addition, subtraction, multiplication and division of complex fraction is relatively complicated and easy to make mistakes. Therefore, in practical problems, fractions and decimals are more often used to express and calculate fractions.

3. Canceling the teaching content of complex fractions can save teaching time and energy, make students concentrate more on mastering more important mathematical concepts and problem-solving methods, and improve the efficiency and quality of mathematics learning.