A diachronic study of language is the description of language at some point in time.

Phonology

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

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

Phonetics

Langue refers to the a（）linguistic system shared by all the members of a speech community while the parole is the concrete use of the conventions and application of the rules.

Pragmatics

Social changes can often bring about language changes.

In the study of linguistics, hypotheses formed should be based on language facts and checked against the observed facts.

Phonetics is different from phonology in that the latter studies the combinations of the sounds to convey meaning in communication.