向盛有一种固态物质中加入一种无色溶液，有气泡产生，装置如右图所示．若生成三种不同的气体，请推测，固态物质可能有三种，化学式分别是______、______、______．无色溶液分别对应是______、______、______．

按括号内的要求改写下列句子。

1. We stopped playing basketball because of the rain yesterday morning.(改为同义句)

    We stopped playing basketball because________ ________yesterday morning.

2. Come here and sit down.(改为委婉语气)

    ________ you ________come here and sit down?

3. No one came to the sale because the weather was bad.(对划线部分提问)

    ________ _________ no one come to the sale?

4. The boy is too young to go to school.(改为同义句)

    The boy is________ young________ he can't go to schoo1.

5. I visit my grandparents once a week.(对划线部分提问)

    ________ _________ do you visit your grandparents?