except 是部分之意，除了．．．．．．就没有．except for 是补充说明这一部分（有set aside之意）就是留出的意思．
eg： 1)There is little we can do except wait and see.
2)Except for the light of his cigarette,the room was completely dark
3)he remained silent during the whole course of the conversation ,except for an occaional "yes"or "um"
4）she likes everyone in her class,except the boy who sits by her
