except和except for在用法上的区别是什么?

两词可以互换,但是except for可置于句首,因此该句选except for
PS:否定句中用except,肯定句式可以用except for来替换
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）