如右图所示，在某一真空中，只有水平向右的匀强电场和竖直向下的重力场，在竖直平面内有初速度为v₀的带电微粒，恰能沿图示虚线由A向B做直线运动．那么(　　)

从方框中选择适当的单词完成短文。

   What's this on the table? It is a ____  of my new classroom. ____  at the picture. ____  can you see ____  the classroom? I can see a ____  desk in the front of the classroom. Some books are ____  the desk. I can see two white ____ , too. There are____  colored chalks (彩色粉笔n them. ____  is the broom (扫帚)? It’s ____  the door. I like this new classroom.

如图为双子叶植物幼茎的横切面示意图，据图回答问题：

如图，AC是菱形ABCD的对角线，AE=EF=FC，则S_△BMN ：S_菱形ABCD的值是（   ）