rules come in different shapes and

rules come in different shapes and
Rules come in different shapes and sizes,but all good rules have something in common – they are specific and easy to understand. 
   “Do” rules.“Walk inside”,“Sit down to eat”,“\Speak in a polite voice”,“Wear the seat belt in the car” and “Be kind to others” are examples of “do” rules.“Do” rules are the best choice in most situations because they tell a child what to do rather than just what not to do.A “Do” rule is a good teaching tool. 
   “Don’t” rules,“Don’t spit” and “Don’t ask for thing in the supermarket” are examples of “don’t” rules.Use “don’t” rules when it is difficult to say exactly what you should do.It is better to have more “do” rules than “don’t” rules. 
    Rules can also be different in different places and at different times. 
    Ground rules,Ground rules apply（适用于） everywhere,no matter what happens.Rules about politeness and hurting others are examples of ground rules.Some ground rules might apply to the whole family,while others may just apply to the children. 
    Situation rules.It can be helpful at times to have some rules for specific situations.You might have rules for traveling in the car,visiting another person’s house,using the computer or something else.