单项选择题
A.60~70% B.70~80% C.80~90% D.85~90%
A.20% B.30% C.35% D.40%
A.喷灌 B.低压管道灌溉 C.微灌 D.波涌灌溉
A.喷灌 B.低压管道灌溉 C.微灌 D.波涌灌
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