1.except与except for有时可以通用,不过,一般情况下,except for可置于句首,而except则不能.如：
Everyone is here except Tom.(或：Except for Tom everyone is here.)除汤姆外,大家都到了.
2.except与except for在句中也可互换.
一般来说,否定句中用except,肯定句式可以用except for来替换.如：
This article has no blunders except a few mistakes.这篇文章除了一点小错外没有大错.
此句可改为：This article is instructive except for a few blunders.这篇文章除了有些错误外,是有教育意义的.
不过,在前后有相称的同类词语时,应用except,否则用except for.如：
We come to school every day except Sunday.除星期天外,我们天天上学.(句中every day与Sunday同类)
This dress is ready except for the buttons.衣服做好了,只是钮扣未缝上.(句中ready与buttons不同类)