成语是长期以来形成的有固定的结构形式和组成成分的定型的词组或短句。大多数的成语是由四个字组成的,例如:“胸有成竹”、“草木皆兵”、“杞人优天”、“自相矛盾”等等也有一部分成语不是四个字的,例如“一窝蜂”、“一举手之劳”、“五十步笑百步”等等,但这只是少数。成语的结构和组成成分都是固定的,约定俗成的,不能随意更换或增减里面某一字词。例如,“千方百计”不能说成“千方万计”;“南腔北调”,不能说成“东腔西调”;可以说“一清二楚”、“七嘴八舌”,但是不能说“七清八楚”、“一嘴二舌”。成语中也有很小一部分在结构和组成成分上古今是有变化的,例如“四通八达”,古时是“四通五达”;古时说“看帆使舵”,现在说“看风使舵”。有些成语,它的几个组成成分习惯上可以互换使用,例如,“一发千钧”可以说成“千钧一发”,“同工异曲”可以说成“异曲同工”,调换后意义不变。还有些成语,在应用时,为了适应某种表达上的需要(如为了强调某种意思和照顾句子的节奏等等),有时也可以灵活 Idioms are long-formed phrases or phrases that have a fixed structure and composition. Most of the idioms consist of four words. For example, “you have a good command of the chest,” “everything is good”, “awesome”, “self-contradictory” and so on. There are also some idioms that are not four-letter, such as “a swarm of bees”. “It takes a lot of effort”, “five steps and laughs and hundreds of steps,” etc. But this is only a minority. The structure and composition of idioms are fixed and conventional, and they can’t be changed or added or subtracted arbitrarily. For example, “doing everything possible” cannot be described as “thousands of thousands of people”; “Southern North-to-North” cannot be said to be “Eastward Westward”; it can be said to be “clear and clear” and “sudden”, but it cannot be said that “seven clear Eight Chu“ and ”mouth-to-mouth“. There are also a small number of idioms that have changed from ancient to modern in terms of structure and composition. For example, the “four directions and eight directions” are used. In ancient times, the “four-way and five-up” were used; in ancient times, “seeing the sail to make the rudder” was said. ”. Some idioms have several components that are customarily used interchangeably. For example, “a thousand generations of people” can be said to be “one in a thousand generations,” and “different ones in the same profession” can be said to be “different to one another.” There are also some idioms that can be used flexibly to adapt to certain expressional needs (such as emphasizing certain meanings and taking care of the rhythm of sentences).