如图4所示，两水平放置的平行金属板M、N放在匀强磁场中，导线ab贴着M、N边缘以速度V向右匀速滑动，当一带电粒子以水平速度V0射入两板间后，能保持匀速直线运动，该带电粒子可能：
A．带正电、速度方向向左
B．带负电、速度方向向左
C．带正电、速度方向向右
D．带负电、速度方向向右
C D
导线ab切割磁感线，上极板带正电，下极板带负电，带电粒子水平向右进入复合场后，洛伦兹力等于电场力，可知CD对；
| 阅读理解。 |
| On National Day, we had a long holiday. We had seven days. I went to Hainan with my parents. My grandparents lived in a beautiful village in Hainan. We visited them. We went to see the blue sea every day. We swam in it. We went fishing. My grandma cooked good food for us every day. The seafood is tasty. I like it. We took many pictures. I was excited. |
| 1. I went to Hainan with my __. |
| A. father and mother B. grandparents C. parent |
| 2. There are _ days on National Day. |
| A. a week B. seven C. five |
| 3. I was __ on National Day. |
| A. very happy B. tired C. bored |
| 4. I can in Hainan. |
| A. went fishing B. swim and go fishing C. went swimming |
| 5. We ate good food . |
| A. last weekend B. every day C. on National Day |