正极板活性物质比较疏松，机械强度低，把正极板夹在负极板中间，可以使其两侧放电均匀，保持正极板工作时不易因活性物质膨胀而变形，造成活性物质（）。
参考答案：脱落
—There is ____ time. You don’t need to hurry. —But I want to see her as early as possible.
A．little
B．plenty
C．a lot
D．plenty of
简述口述史的史学价值。
