wake up的意思是醒醒；醒来；唤醒；弄醒；激起；唤起。例如：A:Wake up, Mum! Smoke! There is a fire in the kitchen. A：醒醒，妈妈！有烟！厨房里着火了。woke up的意思是醒来；开始警觉；开始了解真相。例如：When John woke up and found you gone he went crazy. 

wake up是woke up的原型，woke up是wake up的过去式。