为研究人的活化辅助T细胞对B细胞产生抗体的影响，研究人员将来自于同一豚鼠的B细胞等分为三组．每组培养液中加入的细胞种类如下表所示（“+”表示加入该细胞，“一”表示未加入该细胞）．

将三组细胞在相同条件下培养，在第2、4、6、8、12、14天分别检测A、B、C组上清液中的抗体含量．实验结果为：C组没有检测到抗体，A、B组的结果如图所示．

（1）实验的对照组为____ 组．实验结果显示，B组可从第____ 天起检测到抗体．

（2）A组与B、C组结果相比较，说明____ 不能刺激B细胞活化．

（3）B组与C组结果相比较，说明活化辅助T细胞能____ 

Teenagers growing pains

    Today, our students are facing many different problems and they want to ask some experts for help. Nancy says she feel stressed these days because of too much homework. She hasn't enough time to sleep for a long time and often falls asleep during the classes. John says he doesn't like to study because of the bad effect of computer games. Cindy says she gets fat because she likes to eat junk food and hardly ever takes exercise. Frank has the worst problem. He always fights with others as he doesn't know how to get on well with others and few of his classmates would like to talk with him.

新疆维吾尔自治区位于我国的（    ）