除法有“商不变”的性质，分数有分数的基本性质，你知道比的基本性质是什么吗？你能用含有字母的式子表示比的基本性质吗？

某学校要开展一次生活实践活动，活动组委会邀请你参加部分活动的组织工作。请你完成以下几个任务。

   Nowadays, computer games are becoming more and more popular in many cities and towns.
   A lot of small shops along busy streets have been made into small game houses in order to get more money. These places are always crowded with people, especially young boys.
   In the computer game houses, people spend a lot of money competing（较量） with the machines. It's hard for one to win the computer, but one can make progress after trying again and again. People have a kind of gambling psychology（赌博心理）when they play computer games. The more they lose, the more they want to win. When class is over, the school boys run to the nearby computer game houses. Little by little（渐渐地）, they forget all about their lessons and fall far behind others. Some of them can get enough money from their parents. But some of them are not lucky enough to get the money. They begin to take away other students' money and become thieves.