The boys had put out the campfire,The fire wasn't （）.A.on fire B .alight ,为什么填B ,
问题描述：
The boys had put out the campfire,The fire wasn't （）.A.on fire B .alight ,为什么填B ,
俩个意思那么相近,
答
on fire 是adv（副词）用法.
alight 是 adj（形容词）用法.
原因就像是Baby is asleep/awake.一样
这算是语法,没听说过is后加单个副词（有时会用副词修饰形容词）