A:A球与C球一定带有异种电荷
B:B球可能带电,也可能不带电
C:B球与D球一定带有同种电荷
D:D球可能带电,也可能不带电
我国在2010年进行了第六次人口普查,人口普查属科学探究常用方法中哪种方法?
Yesterday was Sunday. Tom was at home. He got up at six o’clock in the morning. He had rice for breakfast. At eight he helped his mother do the housework. At nine he watched TV with his father. He cooked fish for lunch. At four in the afternoon he washed his clothes. He went to bed at ten in the evening.
中国的历史有多长,中国的茶就有多香.茶文化中有许多的物理知识,例如:
(1)绿茶看起来是绿的,是因为茶叶反射____ ;
(2)通过加热使新鲜茶叶中的水分快速____ ,这便是制茶业中的“杀青”;
(3)用沸水才能很快泡出茶香、茶色,这是因为温度越高,____ 越快.