what is the different in should be or must be.

The words “should” and “must” are modal auxiliary verbs or simply modals. They provide information about the function of the main verb following it. Both “should” and “must” are similar in meaning except that “must” is a much stronger word as compared to “should.” “Should” is the past tense of “shall.”  “Should” is used to denote recommendations, advice, or to talk about what is generally right or wrong within the permissible limits of society. For instance: You should chew your food properly.We should respect our parents.You should stop smoking.You must clean our car regularly. In all these statements, there is a probability or recommendation of some kind. “Must” is used to talk about an obligation or a necessity. It is used when people are compelled to do something. For instance: You must clean the house as your mom is not well. Here, it is imperative that you clean the house or else the house won’t be cleaned and remain untidy. We must obey the law.