1. Jack ________ in the lab when the power cut occurred.

     A. works                                 B. has worked            

     C. was working                                             D. would work  

2. In the spoken English of some areas in the US, the "r" sounds at the end of the    
words ________.

     A. are dropped                          B. drop

     C. are being dropped            D. have dropped

3. In the 1950s in the USA, most families had just one phone at home, and wireless  
phones _______ yet.

     A. haven’t invented                     B. haven’t been invented  

     C. hadn’t invented                                        D. hadn’t been invented