How do you use these orders? Should can be used as a suggestion for something you recommend someone do, but if they don't nothing bad will happen. Must is used like a rule, and would have consequences if not followed. Here are some examples: You should read this book. You must obey the law.

Hi, Should is used when you want yourself / somone to do something but not forcing him. Example: We should think twice before buying this oven. You should not disturb them while they're sleeping. As you can see, if we used must in the above sentences, then it is implying that it is a rule that we must think twice before buying the oven or you cannot disturb people who are sleeping even if it's something important. Must is used when you / someone needs to do something even if the person does not want it. Example: We must respect our elders at all times. You must not go through that door because it is restricted to the kitchen staff only. From the first sentence, we can tell that we must respect people older than ourselves regardless of the situation. The second sentence tells that you are not allowed to go through the door for kitchen staff because it is a rule. Hope you get what I mean.