1, discussion: refers to discussing, commenting or arguing about something or an idea. For example, there was a lot of discussion in the meeting room, and everyone had different views on the plan.

2. Learning theory: refers to the study and discussion of a certain subject or knowledge. For example, this paper made an important contribution to China's ancient literary theory.

3. Argumentation refers to proving the correctness of a viewpoint or conclusion through argumentation and reasoning. For example, this conclusion needs to be fully demonstrated before it can be recognized.

4. Theory: refers to the theory or viewpoint of a system, which usually consists of a series of concepts and principles. For example, modern economic theory plays an important guiding role in the development of market economy.

The function of word combination:

1. Enrich language expression: By combining words, we can create more words and expressions, thus enriching our language and making the expression more vivid, vivid and accurate. For example, beauty and gardens can form a beautiful garden, which makes the expression more concrete and vivid.

2. Help to understand the meaning: The meaning of some Chinese characters may be abstract or difficult to understand, but it can be understood more intuitively when combined with other Chinese characters. For example, the word "ghost" may be unfamiliar, but it is easier to understand its meaning when combined with meditation.

3. Broaden our thinking horizons: Word grouping can not only help us better understand the existing Chinese characters and words, but also stimulate our creativity and imagination and broaden our thinking horizons. Through different combinations, we can create new words and expressions, thus expanding our language ability and thinking ability.

4. Improve the level of Chinese: Word formation is an important part of Chinese learning. Through continuous word formation practice, we can improve our Chinese level and enhance our ability to understand and use Chinese characters and words. At the same time, word formation is also one of the common questions in Chinese examination, and mastering the skills of word formation is also very helpful to improve Chinese performance.