unless 是“除非”的意思,接從句
e.g My boss can't fire me unless he can prove me unsuitable for the job.
except,expect that,都是“除了”的意思
except接名詞.e.g everybody is crying, except you.
except that接從句e.g The plan is perfect, except that it exceeds our budget.
except for 是“要不是因為……”的意思額.e.g She would have travelled more except for lack of money.
besides 有兩種用法.
1、“除了”.這個時候,besides一定要緊跟在句子設定的范圍之后,例如在“expect”的例子中,如果用besides就要說 everybody besides you is crying.而且“except”有比較強的“唯一一個特例”的感覺.
2、besides也可以用作連詞,標轉折,用于句首.