Humans like to live and work in groups. Language is the “cement(胶合剂)”____holds these groups together. Language is part of culture. Culture, in this sense,____ (mean) all those customs, skills, and attitudes that are part of the behavior of a ____ (particularly) group. What you think ____ what you want in life are all affected by the culture of the group in which you ____( raise). Groups of people live in different ways. They may have different skills, organizations, and art forms. Their family life may be completely different from yours.

    Human beings are inventive animals. They can decide to change their cultures in order to meet various ____(situation). Of all living things, human beings are the ____(clever). They can choose ____(live) in many environments and in a wide variety of ways. Only human beings can choose where and how they want to live and then improve the physical environment to help ____(they)realize these choices.

    Acquiring the wisdom to make wise choices ____ (be)the lasting challenge of being human.

“日晷”是一种什么东西，它有什么作用？