题干

两个完全相同的小金属球,它们带异种电荷,电荷量的大小之比为5∶1(两小球皆可视为点电荷),它们在相距一定距离时相互作用力为F1,如果让它们接触后再放回各自原来的位置上,此时相互作用力变为F2,则F1∶F2为(   )

A:5∶2

B:5∶4

C:5∶6

D:5∶9

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答案(点此获取答案解析)

B

同类题3

A)根据下面短文内容,在文章后小题的空格里填入适当的词语,
注意:每空一词。
    Different cultures make different families. For example, there are differences in the way Chinese and Americans raise children.
    First, Chinese and American families have different attitudes towards independence (独立). Each Chinese child has been considered to be the apple of parents' eyes. It is not surprising to see Chinese parents always helping their children with getting dressed, having meals, bathing, and other things. American parents, on the other hand, teach their children how to do things alone from childhood.
    Second, most Chinese parents often make their children have extra classes, such as piano, drawing, or singing lessons. Parents want their children to develop in an all-round way and be better students than other children. The problem is that their children may not be interested in these classes. American parents try to respect (尊重) their children’s interests and usually don't make them do what they don't like.
Third, there is a difference in the way parents in China and American treat mistakes that children make. Many Chinese people believe in the saying, “Spare the rod, spoil the child (不打不成器).” When Chinese parents see their children make mistakes, they often get very angry, some even hit them instead of making them realize their mistakes. This affects the children's growth and the forming of their character, and also makes the generations gap (代沟) wide. American parents think it is common for people to make mistakes because mistakes are a part of life. They often say, “It's OK to make mistakes. Making mistakes helps you learn.” They help their children deal with mistakes by giving them ideas about how to turn mistakes into learning opportunities (机会).
    Families in China and America are quite different, and one way may seem better than the other, but it is better to think about whether the parents fit the family or not instead of talking about which one is wrong or right.

ComparisonsDifferences
Different attitudes
towards  independence
Chinese parents always try to do almost ____ for their children.
American parents try to let their children ____  with things on their own from childhood.
Different ways of treating children's ____ .
Chinese children are often made to go to ____ classes.
American children are usually encouraged to do what they ____ .
Different ways of treating children's mistakes
Chinese parents are____  about children's mistakes and often ____  them.
American parents think everyone can make
mistakes and they are a good ____to learn.
The author's ____
Parenting styles should depend on what is____  for the family.