Past perfect continous tense

         subject                                                                            verb  
*singular or plural 
     subjects                                                                                had been 1 + ing


 ex-
1)They had been building a house for five years .
2)Nimal had been working in that office for ten years.
 3)The doctors had been examining the patients for several   minutes .
 4)They had been going on a tripe for four days.
 5)I had been reading a book yesterday for two hours.





                         question form  
 1)It had been raining for several hours .
2)It hadn't been raining for several hours.
 3)Had it been raining for several hours.
4)Hadn't been raining for several hours.