题目

    At a few minutes past five, Dave noted that the blanket of darkness was lifting. He was just able to make out the heavier masses that eventually appeared as the familiar trees that lined the road at the base of the hill. The upper reaches of the sky showed lighter shades of gray.     Dave got out of bed quietly and dressed quickly. He mixed a spoonful of instant chocolate into a glass of cold water, and his impatience forced him to finish the drink in gulps.     As he walked down toward the lake, Dave paused to reach for the fishing pole and gear box on the bench where he had lef移植植物物幼苗时，总要带一个土坨，这是为了（　　）A.保留水分和无机盐B.避免伤害根冠C.免伤害分生区D.避免伤害根毛和幼根