Science is the process of continuously approaching the truth, and we are convinced that a large part of the unquestionable things will expire, and all who understand this understand that the constant update of knowledge in the development process is the right way for scientific progress. However, this process sometimes Confusing and disturbing. If the following are true, the above questions can be questioned most:. ['Should babies sleep on their backs or on their backs? Is it safe for pregnant women to smoke and drink? The answer is different from one generation to the next.', 'Medical school teachers will tell students that half of what they have learned in five years will not apply.', 'I always thought the name "Thunder Dragon" was correct, but then I realized that there is no Thunder Dragon at all.', 'Smoking is harmful to health is confirmed by a lot of scientific research and facts, this conclusion is difficult to change so far.']