通俗点说,介词就是一种连接词,语法功能是后接名词结构.英语里一共就怎么几个介词：
1. in 2.on 3.under 4.behind 5.at 6.of 7.after 8.between 9.off 10.to 11.with 12.around
13.as 14.by 15.over 16.below 17.about 18.without 19.above 20.before 21.into 22.onto 23.like 24.unlike 25.for 26.beneath 27.from 28.among 29.along 30.within 31.during 32.beside 33.plus ; minus; times
谓语就是对主语的称述或说明,只能由动词结构担当,且一句话只能由一个谓语.
比如这句话：Prepositions are short words (on, in, to) that usually stand in front of nouns (sometimes also in front of gerund verbs).
谓语只有一个就是are,that后面是从句,in of 就是介词
找本语法书看看就好了