防喷器组的结构从上到下为：（）、（）、（）、（）、（）。

( )The meaning representation of words may change，becoming broader, narrower, or shifted．The word knight once meant “youth”，but was elevated in meaning in the age of chivalry；When Juliet tells Romeo，“I’m too fond.” She is not claiming she likes Romeo too much．She means “I am too foolish．”These are two examples of semantic broadening．