Ernest Hemingway, he is seen as one of the greatest 20th century American novelists, served as an ambulance driver during World War I.

 A. The number

 B. are decreasing

 C. that

 D. in

 A. Mr. Forest admitted making a mistake in the calculations.

 B. Mr. Forest admitted having made a mistake in the calculations.

 C. Mr. Forest admitted to having made a mistake in the calculations.

 D. Mr. Forest admitted to have been made a mistake in the calculations.

 A. I was introduced to a man who brother I had seen on TV the evening before.

 B. I was introduced to a man which brother I had seen on TV the evening before.

 C. I was introduced to a man that brother I had seen on TV the evening before.

 D. I was introduced to a man whose brother I had seen on TV the evening before.

 A. for

 B. in

 C. on

 D. with

 A. different

 B. differ

 C. differently

 D. difference

 A. children whom

 B. children

 C. children who

 D. whose children