在单位缺电成本不变的情况下，缺电成本越低，可靠性效益越低。
参考答案：错
某物体的v-t图象如图所示，则该物体
A．做往复运动
B．做匀速直线运动
C．朝某一方向做直线运动
D．以上说法均不正确
—Lu does work hard.
—Yeah. _____ of his time ______been spent on studies every day.
A．Four-fifths; has
B．Four-fifths; have
C．Four-five; has
D．Fourths-five; have
