题目

无土栽培改变了传统农业离不开土壤的限制。实施无土栽培要适时更换营养液，主要目的是为植物生长提供所需的（    ） A.脂肪          B.蛋白质          C.无机盐         D.维生素 答案：CThe doctor suggested that the wounded soldiers _________ to hospital immediately. A. were sent            B. send             C. be sent            D. should send