借助渠堤可实行高水位输水，增大输水能力，扩大送水范围。
参考答案：对
支撑掩护式支架有什么特点？
Which of the following most accurately describes the relationship between marginal cost (MC), average variable cost (AVC), marginal product (MP), and average product (AP)（）
A. When MP＜AP, MC＜AVC.
B. When MP＞AP, MC＞AVC.
C. When MP=AP, MC=AVC.
