1. Those who study without doubt must be taught to have doubts, and those who have doubts must have doubts. Only when they come here can they make progress. -Zhu Xi

2. People who don't ask will always be with ignorance. -East Africa

3. There is no doubt that the key to all science is a question mark. -Balzac

4. Questioning is the first step towards philosophy. -Diderot

5. Scholars must be suspicious first. -Cheng Yi

6. There is no doubt that if you are a student, you will make progress if you doubt, small doubts will make small progress, and big doubts will make great progress. -Lu Jiuyuan (Song)

7. The spirit of doubt is an important part of the scientific spirit. -Zhou Guangzhao

8. He who is good at doubting does not doubt what others suspect, but what suspects do not doubt. -Fang Yizhi

9. A inquisitive person is like tackling a difficult problem. The first one is easy, the second one is self-restraint, and it takes a long time to explain. He who is not good at asking questions is the opposite. The problem is the midwife, which can help the birth of new ideas. -Socrates

11. Those who are suspicious and not suspicious have never learned; Learning requires doubt. -Zhang zai

12. Doubt is the beginning of thinking and the end of learning. -Confucius

13. Teachers should question and friends should analyze doubts. -Li Xing

14. Asking questions is more important than solving them. -Einstein

15. The spirit of doubt is an important part of the scientific spirit. -Zhou Guangzhao