介詞用來表明名詞、代詞與句中其它詞的關系的詞叫做介詞。（是虛詞，不能重讀，不做單獨做句子成份）根據構成形式分，簡單介詞由一個詞構成，如at, on, in, after, before, behind等；合成介詞由兩個詞合成在一起，如inside, outside, into, without, nearby等；雙重介詞由兩個簡單介詞重疊在一起，如from behind, until after, from among等；短語介詞由一個或幾個簡單介詞和一個或幾個其它詞組合而成，如at the back of, instead of, in place of, in front of, at the top of等；動詞－ing形式介詞，如including, considering, regarding, concerning等。介詞可以根據意義分類。表示空間關系的有on, under, in, outside, in front of, behind, round, around, by等；表示時間的有at, off, throughout, underneath, as, between, since, until, during, till, for, before, after, from…to…, across, up, over, past等；表示方位的有beyond, opposite, onto, into, towards, through, against, along等；表示手段、施動者等的有like, in, by, with等；表示其它含義的有without, with, except, beside, of, another, instead of, plus, minus, like, unlike, but, from, according to, of course, per, about等。連詞用來連接單詞、短語或句子的一種虛詞，在句子中不單獨作任何成份，一般不重讀。連詞可以根據構成成分分，簡單連詞包括and, or, but, if, because, so等；關聯連詞包括both…and, not only…but also…, not…but…等。連詞還可以按性質分類。并列連詞包括and, or, but, for, while, when, however, as, nor等；從屬連詞包括whether, though, until, after, although, when, since, unless, because, before, that, if, when, as though, as if, even though, as long as, even if, so, than, whenever, wherever, which等。