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.

Morphology studies how words can be formed to produce meaningful sentences.

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.

Chomsky defines “competence” as the ideal user’s k（）of the rules of his language.

Linguistics

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

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

Language

Modern linguistics is mostly prescriptive, but sometimes descriptive.

Phonology