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

The study of the ways in which morphemes can be combined to form words is called morphology.

General linguistics is generally the study of language as a whole.

Syntax

Both semantics and pragmatics study meanings.

The distinction between competence and performance was proposed by F. de Saussure.

Phonetics

Morphology

Semantics

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.