5. A. helps B. existed C. helped D. did

4. A. figure it out B. think them out

C. get them through D. solve it

3. A. set out B. unable C. start D. unwilling

2. A. the classroom B. the chalkboard

C. the teachers' office D. their seats

10. The boy stood there ________ his eyes fixed ________ the cake.

9. Scientists have found out the way the brain works is not so simple as people ________ general may think.

8. It is well known that the giant panda is native ________ China.

7. The man she is engaged ________ is engaged ________ research work.

6. Other doctors, however, point ________ that there is more danger of a heart attack during summer swimming because the difference ________ the air temperature and water temperature is much greater in summer than in winter.