except ,except for ,besides ,but 区别

except：指同一类事物的总体中除去一部分.
He gets up early everyday except Sunday.
except for表示“除了…”,它引出一个与前面的词相反的原因或者事例.
The room was very cold and,except for Jack,entirely empty.
Except for one old lady,the bus was empty.
besides:强调“除此之外,还包括”.
She can speak French and Japanese besides English.
Besides milk and cheese,we need vegetables.
but：常可与 except互换,强调“不在其中”.
Everyone attended the meeting but Mary.
No one but me passed the exam yesterday.昨天除了我以外没别人考及格.