20. More and more high-rise buildings have been built in big cities (   ) space.

• A、in search of 

• B、 in place of 

• C、 for lack of

• D、for fear of

42. At last Jim's mother (   ).

• A、gave her son some good food

• B、knew her son had told a lie

• C、 bought some medicine for her son

• D、 bought some cakes for her son

51 (   )