在甲、乙、丙三个培养皿中分别放入等量的面巾纸，在面巾纸的上面都放25粒绿豆种子，然后将它们放在不同条件下进行培养，数日后记录种子萌发的情况如表．

据表分析可知，该实验的实验变量是（　　）

分析资料，回答相关问题：

资料一：2014年春季，手足口病卷土重来，该病是近几年临床上较多见的一种由肠道病毒引起的传染病，而且易感人群不再局限为幼儿，已成年患者的不断出现，使得手足口病再次引发人们的关注．

资料二：近年来，越来越多的人喜欢养狗、猫等宠物，这为狂犬病传播带来隐患．我市狂犬病发病率呈逐年上升趋势．狂犬病患者一旦发病几乎全部死亡．专家提醒：如被宠物咬伤，应在24小时内注射狂犬病疫苗．

资料三：几年前曾经肆虐的甲流，因为甲流疫苗的广泛使用而得到了有效遏制，而没有接种过甲流疫苗的人则往往容易患病．

    Teachers say buying homework answers online is not many in schools, but an interview with school students shows only 10% are willing to finish their holiday homework by themselves.
    Their main complaint is that the homework is too much for them to finish.
    “As far as I know, many of my students have to go to all kinds of training classes during the holiday. These take away much of their time for doing homework.”
    But as for the parents  who are sending their children to these training classes  they also say they've got no choice. Here's a view from a student's father.
    "All the other kids in the neighborhood are learning extra things. You know parents sometimes compare their kids. I'm afraid my kid will be less successful than the others in the future."
    In order to do with this situation of students copying each other's homework, some schools have even dropped the idea of holiday homework. Instead, they organize some interesting outdoor activities.
     Educational experts say students love to learn through games or activities that they can be a part of. They suggest schools drop the current (目前的）homework format (设计)，and turn to homework that encourages kids to get involved (参与).This way, they would no longer want to copy from each other or buy answers through the Internet.
    Answer the following questions according to what you read.