Flat-Footed: A creature that hasn’t yet taken an action during combat is flat-footed, not yet able to react normally to the situation. A fl at-footed creature is denied its Dexterity
bonus to AC and can’t make attacks of opportunity.
Flat-footed AC = AC – Dex bonus – dodge bonuses
You can’t use an immediate action when you’re fl at-footed.
这几句基本就是措手不及的所有效果了