title: 英语单项选择Whywereyousolate?Ourclassw 
desc:  Why were you so late ? Our classwill begin now .
  I'm sorry .I -- my  book .
  A have looked for  B had looked for
  C looked for       D was lookingfor 
answer: 这是一道语法题。应该选D。
  完成这道题目的关键是理解过去进行时(the past continuous tense)的意义：它表示过去某个时间某事正在进行，过去时间可由一时间状语表示，相当于现在进行时的过去形式。
  比如：I was having a shower at that time.
  
  题目中的were要特别注意！他没有说"Why are you so late?"所以就是对过去某一时段在做的事情进行提问。当然要用过去进行时咯！