Findings in linguistic studies can often be applied to the settlement of some practical problems. The study of such applications is generally known as a（）linguistics.

填空题P （）refers to the realization of langue in actual use.

填空题Human capacity for language has a g（）basis, but the details of language have to be taught and learned.

填空题The discipline that studies the rules governing the formation of words into permissible sentences in languages is called s（）

填空题Language is a system of a（）vocal symbols used for human communication.

填空题D（）is one of the design features of human language which refers to the phenomenon that language consists of two levels: a lower level of meaningless individual sounds and a higher level of meaningful units.