18)   A there was     B that was           C it was           D was

19)   A know        B knew            C have known       D had known

20)   A so will the time be              B the mine will be,too     

         C so will mine                       D mine will be,too

答案:

1--5 BAACA 
6--10 DDDAC  
11--15 CABAD   
16--20ACCDC