题目

Teenagers are known for being creative and full of new ideas. Let’s have a look at these teenage inventions that might change the world.Banana leaves usually go bad in two or three days. Tenith Adithyaa, a teenager from India, used UV to make the leaves stay fresh for a year. Tenith thinks that one day the leaves will be used for making plates, cups and other things. David Cohen, an American teenager, built an earthworm(蚯蚓) robot. It is able to go into the smallest places, where humans or dogs can’t go. It will be used for finding people in a fire or an earthquake. Remya Jose, a 14-yea实验员在课前临时给化学教师准备了一套乙醛性质实验和洗涤银镜的药品：NaOH、氨水、CuSO4、AgNO3、稀HNO3、乙醛六瓶规定浓度的溶液。由于时间仓促，仅在盛乙醛的试剂瓶上贴了标签。但这位老师在演示实验时每次都能准确地选取所需药品。他辩认药品的方法是：　　　　　　　　　　　　　　　　　　　　  。