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