You can go out,----you promise to be back before 11 o'clock.

You can go out,____you promise to be back before 11 o'clock.
A.except除了 后面不能接句子
B.as long as 只要 可以接句子
C.unless 除非 但是如果用它,前面要用否定 即：
You can not go out _unless___you promise to be back before 11 o'clock.
D.so that 所以 不符合句子意思
只有Bas long as 翻译：只要你保证在11点前回来,你就可以出去!