Complete the following statements with proper words or expressio

Complete the following statements with proper words or expressions according to the course book.​The vocabulary of a language is in constant change; old items drop out, new items come in, and as the new replace the old, so the internal ( ) of the whole set alter.
【正确答案】：RELATIONS
【题目解析】：​一种语言的词汇是不断变化的；旧的词条退出，新的词条出现，随着新的取代旧的，所以整个集合的内部关系改变了。