C. by    D. ahead of    16. If you hear the fire _____, leave the building quickly.    A. warning    B. alarm    C. signal    D. bell    17. The troops have been on the _____ for a possible enemy attack.    A. alarm    B. alert    C. warning    D. notice    18. Although his people did not _____ his efforts, he kept trying.    A. agree with    B. apply to    C. approve of    D. consent with    19. Picasso's _____ ability was apparent in his early youth when he started drawing sketches.    A. writing    B. artistic    C. reasoning    D. literary    20. We hope that the measures to control prices, _____ taken by the government, will succeed.    A. when    B. since    C. after    D. as |