A:①②⑤
B:①③④
C:②③④
D:①③⑤
某同学做“馒头在口腔中的变化”的实验,具体过程如下,回答有关问题:
请回答下列问题:(1)为了证明“唾液对馒头有消化作用”,在2号试管的A处应加入____ ,与1号试管起____ 作用。(2)为了证明“牙齿的咀嚼,舌的搅拌”对馒头有消化作用,应选用____ 两支试管进行对照实验。(3)实验结果是____ 号试管中的物质遇到碘液不变蓝,原因是____ 。(4)通过以上实验可知,口腔对淀粉既能进行____ 消化,又能进行____ 消化。
从方框中选择适当的单词完成短文。
What's this on the table? It is a ____ of my new classroom. ____ at the picture. ____ can you see ____ the classroom? I can see a ____ desk in the front of the classroom. Some books are ____ the desk. I can see two white ____ , too. There are____ colored chalks (彩色粉笔n them. ____ is the broom (扫帚)? It’s ____ the door. I like this new classroom.
下列生活事例中,主要过程为化学变化的是( )