根据爱因斯坦的相对论可知，任何物体的运动速度不能超过光速（3×10⁵km/s），因为一个物体达到光速需要无穷多的能量，并且时光会倒流，这在现实中是不可能的．但我们可让一个虚拟物超光速运动，例如：直线l，m表示两条木棒相交成的锐角的度数为10°，它们分别以与自身垂直的方向向两侧平移时，它们的交点A也随着移动（如图箭头所示），如果两条直线的移动速度都是光速的0.2倍，则交点A的移动速度是光速的____倍．（结果保留两个有效数字）．

下列属于被子植物中的十字花科植物的是（    ）

阅读下列材料

北方人看不惯南方人，南方人不服北方人。……当前南北之间的矛盾不是别的，而是两种社会制度之间的斗争。这外斗争之所以爆发，是因为这两种制度不能再在北美大陆上和平共处了。

——马克思《美国内战》

请回答：

下列物体的运动状态没有发生改变的是（  ）

短文填空。

    On weekends, everyone is at home but each is doing their own things. It's ____ to get everyone together and do something as a family. What should parents do? Here are some suggestions.

Exercise outside

    Let children ____ their bikes or just hang out in the open air. You can also just ____ a walk together with other family members. It is great exercise. And it is good for ____ .

Play a game

    Games should depend on the kid's ages. For elder kids, the father can ____ chess with them. If your kids are ____ , a game of memory is perfect. If you can't play the games, you can always draw ____ on cards and make up your own game.

Go out for supper

    Going out for supper not only gives mom a break, but also offers a lot more time to ____ about the past week together.

Make a photo album

    Go through all those old ____ that are just lying around and get them into a book. ____ you have a few kids, let each one do a page of their own. It can be as simple as sticking them in a book.

Hope you enjoy these ideas and will enjoy doing these activities with your family!