提高草原生态系统的稳定性，应采取的措施是[ ]
A．喷施农药消灭害虫
B．不准放牧
C．建立草场防护林
D．严禁割草
答案：C
I _____ him to give up drinking, but he wouldn't listen to me. [ ]
A. persuaded
B. tried to persuade
C. advised to persuade
D. tried to advise
土壤耕作措施的选用与配套应看（）。
A．看天
B．看地
C．看庄稼
D．看经济效益
