ways of spending free time. Sometimes they just want to have a rest, but they try to do something more pleasant most of the time. They have many different hobbies, which help them to get away from their everyday problems and spend their free time happily.

Many Polish people like traveling. They look for new places that they have never been to and add new and exciting experiences to their journey. Some of them like to climb mountains,. others like to go to the sea or a lake to swim, because theses can make them get exercise and are good for their health.

Many Polish people also like to do sports in their free time. They are usually crazy about football, and football is regarded as the Polish national sport. Many football fans may support a certain team ,so they go to watch every match of the team they support, and they buy many things that have any relation with the team. Watching sport and doing it are both good ways to relax

In addition, doctors say that doing sports is very good for the health. Many people in town, especially young men, often go to the gym to attend the exercise classes to keep fit.

Besides these ways, Polish people have many other ways to spend their free time . And they really enjoy their free time.

电源《阿凡达》中的发光植物为我们打造了一幅绚丽、梦幻的外星世界景观．现在，这种会自发光的植物已经被科学家带到了现实生活中．据报道，美国科学家近来利用生物技术成功培育出了名为“星光阿凡达”的发光烟草，它甚至可以代替灯泡来照明．

（1）科学家将海洋发光细菌的DNA片段引入烟草中，对野草进行了基因改良，使其能够自然、主动、持续的发光，这种技术称为____ ．

（2）自发光是烟草通过生物技术获得的性状，说明生物性状受____ 控制．

（3）烟草花色的红色和黄色是一对相对性状．红花烟草和黄花烟草杂交，后代全部是红花烟草（如图）由此判断____ 是显性性状．

（4）烟草花叶病毒能够引起烟草叶出现黄绿相间的病斑，即烟草花叶病．该病毒结构简单，仅由蛋白质外壳和RNA（核糖核酸）组成．以下是烟草花叶病毒浸染烟叶的实验：

烟草花叶病毒烟叶烟叶出现病斑烟草花叶病毒

烟草花叶病毒的蛋白质外壳烟叶正常烟叶无烟草花叶病毒

烟草花叶病毒的RNA烟叶烟叶出现病斑烟草花叶病毒

以上实验结果说明：烟草花叶病毒的遗传物质是　____ ．

（5）如果烟草花叶病毒浸染“星光阿凡达”发光烟草．理论上发光烟草是否会感染烟草花叶病？____ 

一个不透明的袋子中只装有3个黑球，2个白球，这些球的形状、大小、质地等完全相同，即除颜色外无其他差别．在看不到球的条件下，随机从袋中摸出1个球，则摸出白球的概率是____ .

请为下列实验操作各选一种仪器（填写相应的序号）：

吸取或滴加少量液体时用____；可以直接在酒精灯火焰上加热的玻璃仪器是____；硫在氧气中燃烧的实验用____；量取8mL的水用____．

11封信投入3个邮箱里，至少有4封信投入同一个信箱里，为什么？（用自己喜欢的方式说明）