从下面两个作业中选择其中一个完成： （1）自制双轨怪坡。用筷子（或其它木棍等）组成一个双轨怪坡，用玻璃弹珠（或其它小球）放在怪坡上，操作两根筷子使弹珠上滚。 （2）表演“纸顶硬币”实验。用一张纸片（或名片等）对折竖直放置，把一枚硬币（或其它小物品）放置其上，慢慢拉直纸片使硬币不掉落。

作业A：People use mobile phone for different purposes. Some people, most of which are students, use their phones to study online. Most apply their phones for fun, like playing games or watch videos. While, some businessmen do their work via phones, instead. In my case, my phone is regarded by me as a tool for my work.作业B：I like dogs, so does my best friend.Iwillnotshow offmy beauty.That'snothingtoboastof. 我不想夸耀自己的美腻~Thereisnodishtogowithrice. 没菜配饭。