The covariation method of traditional inductive logic refers to that if only one situation changes on several occasions where the phenomenon under study changes, then the only change is the cause or effect of the phenomenon under study. According to the above definitions, the covariation method is used in the following inductions:. ["A pharmaceutical company's drug is tried by 1,000 people of different genders, ages, and physical conditions. No one has side effects. Therefore, taking this drug will not cause side effects.", 'In 1917, American physiologist Jacques Loeb et al. Found that under other conditions unchanged and normal temperature changes, the lifespan of fruit flies can be doubled for every 8 ° C decrease in temperature. It can be concluded that Drosophila lifespan is related to temperature.', 'People have long thought that "swans are white. " After discovering that there are black swans in Australia, people know that "swans are not all white. ".', 'A colleague of Pierre Curie put a small glass filled with radium reagent in his underwear pocket for several hours. After a few days, he noticed that the skin next to the underwear pocket was red. Curie also did one on himself. A series of experiments showed the same results. He concluded that the skin damage was caused by radium rays.']