1) besides 表示“除 … 以外,（还,也）”
Besides English, they also study math, physics and chemistry
除了英语以外,他们还学习数学,物理和化学.
2) except 表示“除…外,（其余都）…”
He answered all the questions except the last one.
除了最后一个问题外,所有的问题他都回答了.
3)except for 也表示“除 … 以外”
Your composition is good except for a few spelling mistakes.
除了几处拼写错误以外, 你的作文写得很好.
4)in addition to“除……外（还）”,相当于besides.
He speaks French in addition to English.
除了英语他还会说法语.
再问： 我知道他们的意思，我问的是指用法的区别，能说清楚点吗？
再答： 1）(肯定)表示“除……之外(还)……” besides 和 in addition to 同义 She knows Japanese besides English. In addition to English, she knows Japanese. 2）(否定)当与nothing，nobody或no one等否定意义的不定代词连用时，表示“除…之外(其余都不)”。 besides与except同义， except 表示“除……外，(其余都)……”，常与“all，every，no，none，nothing”等含有整体肯定或否定意义的词连用。 All of them went to climb the mountain except me. 3）except for： 它的宾语与前述对象完全是两回事。 The room was very cold and, except for Jack, entirely empty完全是空荡荡的. 4）except：指同一类事物的总体中除去一部分。 He gets up early everyday except Sunday. 5) except that 后面跟从句，语意与上同。 He has always been in good health except that he has had a slight headache in the past few days. 6）but：常可与 except互换，强调“不在其中”。 Everyone attended the meeting but Mary. 7）besides:强调“除此之外，还包括”。 She can speak French and Japanese besides English. 8）apart from；其含义主要依据上下文而定，有时可与except换用，有时可代替besides. Apart from the price, the hat doesn't suit me. 9）except 用于同类之间。 except for 用于不同类的。 apart from 在同类或不同类都能用 10）except for和apart from接名词, 但apart from是从"什么分离出来"的意思 而except for是"除了"的意思
