题目

Today, there are many problems between parents and children. Many people always ask, “why do we often argue(争论)?” Parents show their love for their children in different ways. They cook nice food, buy new clothes for them. They also care about their studies. Parents always say “You must work hard.” “You should do your homework，” “Why not prepare for your exam?” When children get bad marks, their parents get very angry. They often stop their children from watching TV, playing computer games or even going outside until they are good at their studies.Why? Most families have 2．一个布袋里装有大小相同的8个球，其中白球5个，红球3个．如果从这个袋中任取1个球，取到红球的可能性是$\frac{（\;\;\;\;）}{（\;\;\;\;）}$．如果摸40次，那么摸到白球可能有25次．