先看两个句子：
1.Except for a few words he didn't say anything.
2.Everyone is here except Jimmy.
从这两个句子就可以看出区别了：
1.everyone 和 Jimmy 都是人,属同类事物,用except,再如：
We go to school every day except Sunday.
这种用法表示：从整体中减除部分.
2.word 和 anything 不属于同类事物,用 except for ,再如：
Your composition is good except for some spelling mistakes.composition 和 mistakes 不属于同类事物.
这种用法表示：对整体说明做细节修正.
2)当except用在句首时往往改用exceptfor.例如:
There was no single person in the dark street that night except apoliceman on his duty.此句相当于:
Except for apoliceman on his duty,there was no single person in the dark street that night.
因此不能用except只能选apart from