耕作制度是指一个地区或单位以作物种植制度为中心，为保证农作物全面持续增产，所采取的用地与养地相结合的综合农业技术体系。（）
参考答案：对
Helen ________ her keys in the office so she had to wait until her husband ______ home.
A．has left; comes
B．left; had come
C．had left; came
D．had left; would come
对于危害电力设施安全的行为，电力企业有权（）
A、责其恢复原状。
B、强行排除妨害。
C、责令赔偿损失。
D、劝其改正。
