A、They smile to cover embarrassment. B、It is an unusual and even suspicious behavior. C、They smile to show politeness. D、It is a

Facial expressions carry meaning that is determined by situations and relationships. For instance, in American culture the smile is typically an expression of pleasure. Yet it also has other functions. A smile may show affection, convey politeness, or disguise true feelings. It is also a source of confusion across cultures. For example, many people in Russia consider smiling at strangers in public to be unusual and even suspicious behaviour. Yet many Americans smile freely at strangers in public places. Some Russians believe that Americans  smile in the wrong place; some Americans believe that Russians don’t smile enough. In Southeast Asian cultures, a smile is frequently used to cover emotional pain or embarrassment.
    Our faces reveal emotions and attitudes, but we should not attempt to "read" people from another culture as we would "read" someone from our own culture. The degree of facial expressiveness one exhibits varies among individuals and cultures. The fact that members of one culture do not express their emotions as openly as do members of another does not mean that they do not experience emotions. Rather, there are cultural restraints on the amount of nonverbal expressiveness permitted.
    If we judge people whose ways of showing emotions are different according to our own cultural norms, we may make the mistake of "reading" the other person incorrectly.