20. Question, rather than question, "Real singers can sing out the silence in people's hearts." ——Chai Jing

21. Doubt is the beginning of thinking and the end of learning. ——Confucius

22. Doubt is the key to knowledge——(UK)

23. When reading, there is doubt in the unknown; secondly, doubt gradually arises; in the middle, there is integrity Judgment is doubt. After this, doubts will gradually be cleared up, until you have a comprehensive understanding and no doubts at all, and that is when learning begins. ——Zhu Xi

24. A smart person will always ask questions. ——India

25. Deep in the human heart, there is a deep-rooted need, which is to hope that oneself is a discoverer, researcher, and explorer. In the spiritual world of children, this need is particularly strong. ——Suhomlinsky

26. It is problems that inspire us to learn, practice, and observe. ——Bobol

27. If a person starts with affirmation, he will end with doubt; if he prepares to start with doubt, he will end with affirmation——(UK)

28. A smart person will always ask questions——(India)

29. Asking the right questions is often equal to solving most of the problems——(Heisenberg)

30 , Creation starts with problems. Only when you have problems can you think. Only with thinking can you have methods to solve problems and the possibility of finding independent ideas. ——Tao Xingzhi

31. Those who do not doubt when there is doubt have never learned; learning requires doubt. ——Zhang Zai

32. People who know nothing will not doubt anything. ——Britain

33. People who don’t ask will always be together with ignorance. ——East Africa

34. To solve the problem, systematic and thorough investigation and research work must be done. This is the process of analysis. Asking the question is where the contradiction lies.

35. There is no doubt that there will be doubts in learning. If there is doubt, there will be progress. If there is little doubt, there will be small progress. If there is great doubt, there will be great progress. ——Lu Jiuyuan (Song Dynasty)

36. The problem is the midwife, it can help the birth of new ideas. ——Socrates

37. Doubt is the key to knowledge. ——Britain

38. Doubt can destroy yesterday’s faith and open the way for tomorrow’s faith—(Romain Rolland)

39. Without doubt, you cannot see the truth. ——Li Siguang

40. A person who is eager to ask questions is only five kinds of fools; a person who is ashamed to ask questions will be a fool for life. ——Anonymous