When words are grouped together，those word groups may be categorized as phrases or as clauses．A clause is a group of words containing a subject and a predicate．A phrase does not have a subject and a predicate．Such a word group always functions as a single part of speech—for example，a noun，an adjective，or a verb．

若干词连接在一起，就形成分句或短语。分句是一种由词组构成的“主语+谓语”的结构。词组中却不包含主语和谓语。词组的功能只能相当于名词、动词或形容词等某一词类。