43. The students began to do the volunteer work last summer.
    A. The students haven’t done the volunteer work since last summer.
    B. The students have done the volunteer work last summer.
    C. The students have done the volunteer work since last summer.
    D. The students have done the volunteer work for last summer.
44. He started living here in 2000. 
       A. He lived here in 2000.
       B. He has lived here since 2000.     
       C. He has been living here since 2000.          
        D. He has lived here for 2000. 
45. last time I saw Rose was three years ago.
        A. I didn’t see Rose for three years.        
        B. I haven’t seen Rose three years ago.
        C. I haven’t seen Rose since three years.      
          D. I haven’t seen Rose for three years.