A preposition is a word such as "by," "for," "into," or "with" that usually has a noun group as its object. 介词
noun [专属名词] 介词，前置词
There is nothing in the rules of grammar to suggest that ending a sentence with a preposition is wrong. 在语法规则中没有哪一条表明以介词结束一个句子是错误的。
pre(…前的)+position(地点， 位置)→介词通常都是加在方位之前→介词
