如图所示，充电的两平行金属板间有场强为E的匀强电场和方向与电场垂直（垂直纸面向里）的匀强磁场，磁感应强度为B，构成速度选择器，氕、氘、氚核以相同的动能E_k从两极板中间垂直于电场和磁场射入速度选择器，且氘核沿直线射出，则射出时（   ）

关于美国某汽车制造车间的描述：“许多零部件是由韩国提供的，钢材是用巴西的铁矿石炼制的，制造轮胎的橡胶来自泰国，部分工人来自墨西哥”，这说明了（    ）

    Mr. Jones teaches history. He is a very good teacher. During this year, most of his students got at least a C on the tests and there were many A's. On the last test, however, Mr. Jones got a big surprise. He wrote down all of his students' scores. Then he counted the number of students that got between 91 and 100. There were only two! Only two students got A's! He found out that there were only a few B's and C's. Most of the students in his class got a D or and F on the final test. Mr. Jones looked at the test again. He thought that it was too hard. He decided to give every student 10 more points. Then many of the students got good grades on the test. What a nice teacher!

抄写词语。

        源源不断                       绿草如茵                      不毛之地