Ever since humans lived on the earth,they have made use____various forms of communication.In general,the major form of expressing thoughts and feelings____(be) spoken language.____there is a language barrier, communication is completed through body language.Smile is the most universal____(face) expression,which shows happiness and puts people a ease.But sometimes,it is likely to hide other feelings,like____(angry) and worry.There ____(be) different ways to greet someone in different countries.People from Columbia like approaching others and kiss them on____cheek.In France,if adults meet people they know,they can kiss each other twice on each cheek. Being polite to others is____(object),but we'd better not give a hug to a person with higher rank.Body language is ____(real) complex, so we should study international customs____(avoid) difficulties in today's world of cultural crossroads.