下列说法正确的是
A．有些晶体是由分子直接构成的，如干冰、白磷等；有些晶体是由原子直接构成的，如金刚石、重晶石等；有些晶体是由离子直接构成的，如食盐、纯碱等
B．分子是保持物质性质的一种微粒，也是化学变化中的最小微粒
C．金刚石晶体和甲烷分子中的碳原子的杂化类型都是sp3杂化
D．H2O 是一种非常稳定的化合物，这是由于氢键所致
答案：C
A：重晶石是硫酸钡，离子化合物，由离子构成
B：原子是化学变化中最小微粒
C：正确
D：水之所以稳定是由于其分子内的化合键牢固所致，而氢键一般与物理性质有关
答案为C
| 阅读短文，根据短文内容补全表格中所缺的信息，每空一词。 | ||||||||
| Do you still get free plastic bags (熟料袋) from the supermarkets? Things have changed. China has decided to take action to stop the use of free plastic bags at shops and supermarkets, and people have to pay for using plastic bags. The rule (规定) started on June 1. It came because our country tried to make litter less. The Chinese once used about 3,000,000,000 plastic shopping bags a day, and they made the environment pollution more serious and wasted a lot of energy as well. People throw the used plastic bags away here and there. The thrown-away plastic bags are not easy to break.So the Chinese government encourages people to bring their own bags or baskets for shopping. What kind of shopping bag is the best to bring? Some students have good ideas. They make their own shopping bags. They use old clothes to make cloth bags (布袋), and send them to their parents as presents. They also ask their parents and friends to use cloth bags instead of plastic ones. They think it is their duty to protect the environment. | ||||||||
|