A:先将玻片标本往右上方移动;再转动转换器,把高倍物镜换成低倍物镜
B:先将玻片标本往左下方移动;再转动转换器,把低倍物镜换成高倍物镜
C:先将玻片标本往右上方移动;再转动转换器,把低倍物镜换成高倍物镜
D:先将玻片标本往左下方移动;再转动转换器,把高倍物镜换成低倍物镜
People in the West didn't know coffee or tea two hundred years ago. They were 1 to drink them because they thought coffee or tea could kill a person. Once the king of England decided to find out 2 it was true.
There were two brothers in prison(监狱) at that time.They would be killed 3 a few days because they did wrong. The king said, "I shall let them live but they must drink coffee or tea to the end of their lives. One brother must drink coffee and 4 must drink tea every day." And they followed the king's words.
They both lived many years. At last, the elder brother died when he was eighty-three years old.The younger one died a few years later. After that, people 5 that coffee and tea were not bad to man.
下面是一个正方体,用一个平面去截这个正方体截面形状不可能为下图中的( )