阅读理解

Everybody wants to be healthy. You know food is very important. There are lots of healthy food. You can have more bananas, apples, oranges, tomatoes and lettuce because fruit and vegetables are good for you. But don’t eat too much chocolate. It’s not healthy food. Healthy food can make you grow (生长) and make you strong（强壮的） and happy. Remember there is a saying—“An apple a day keeps the doctor away（远离）”. Sports can also keep you healthy. Get up early and do some sports every day. Don’t be lazy（懒惰的）. You will be healthy and happy.

It is black ______ white. （  ）

①若要验证小莹同学的猜想：可向反应后的溶液中加入金属____，结果发现在该金属表面只生成红色固体，则证明该同学的猜想是错误的．

②因为稀盐酸是新配制的，不存在变质的可能，所以小斌同学的猜想也是错误的．

③小歆为了验证自己的猜想是正确的，在不改变药品和实验方法前提下，向实验结束后的试管中加入某种物质适量，结果发现溶液呈现蓝色．小歆加入的是下列哪种物质____

A．酒精     B．水     C．硫酸铜溶液     D．氯化铜溶液

爱动脑筋的小歆对这一实验做了一点改进，将一根铜丝擦光亮后，一端绕成螺旋状放在酒精灯火焰上灼烧至表面出现黑色，然后趁热放进稀盐酸中，一会儿就可以看到螺旋上的____，溶液也由无色变成蓝色．化学方程式____

如图是抛物线y=ax²+bx+c的大致图象，则一元二次方程ax²+bx+c=0（　　）