1. The problem _ when the students refused to do their homework. A. arose B. aroused C. rose D. raised 2. When he suddenly _ up the subject of genetic engineering, there was an embarrassed silence. A. took B. brought C. showed D. came 3. _ so many people in the United States been out of work as today. A. More than ever before B. In the past, there have never C. Never before have D. Formerly, there never were 4. It _ as a shock
