title: 选择a,b或cHadTomstudiedharder,he()t 
desc: Had Tom studi harder,he (     )the exam.(a.must have got throuh b.would have got through c.would get through)
answer: 这是虚拟语气，选b.
  整句话这样理解：要是TOM努力学习的话，他早就通过考试了。
  与过去事实相反，从句应用过去完成时，主句过去将来进行时。（这是规则,请务必记住）