He said the idea came to him when he observed that the coasts of South America and Africa could fit together like two pieces of a puzzle.

VOA: special.2010.01.12

But Pavlov observed that when somebody entered the room who typically gave him the food powder, the dog--the food powder saliva would start to come out.

他注意到,当给它喂食的人,进屋时，狗便开始分泌唾液。

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