题目

Why do we dream? It’s a question researchers have been studying for years. Now new research suggests that some dreams may result from the brain’s effort to keep learning, even as we sleep.In a study in Boston,100 volunteers were trained for an hour on a maze(迷宫). They tried to find their way through the difficult puzzle as quickly as possible. Then half of the volunteers were allowed to sleep for 90 minutes. The other half stayed awake, reading or relaxing. The ones who slept were asked to describe their dreams when they woke up.After the rest, the volunteers were asked again to solve 3．如图为某同学利用紫色洋葱鳞片叶作为实验材料，观察植物细胞质壁分离与复原的基本操作步骤．下列相关叙述中，错误的是（　　）A．第二次观察（d）和第一次观察（b）形成对照，第三次观察（f）和第二次观察（d）形成对照B．该实验用显微镜主要观察原生质层和细胞壁的位置关系、液泡的颜色和大小等C．增大蔗糖溶液的浓度会使第二次观察（d）和第三次观察（f）实验效果更明显D．如果将蔗糖溶液换成浓度适宜的KNO3溶液，则可以省略e过程