关于except的几个问题1.For miles and miles wo could see nothing （but

关于except的几个问题
1.For miles and miles wo could see nothing （but ）a great fire.
为什么不用escept for?
2.I know nothing about the young lady（ except that ）she is from Beijing
为什么不用except when?
3.I knew nothing about the accident（ except what） I read in the newspaper
为什么不用except when?
4.（except for ）an lady,the bus is empty
为什么不用besides?