问题 选择题

下列含有非极性键的共价化合物是

A.H2O2

B.Na2O2

C.H2

D.CH4

答案

答案:A

B为离子化合物,排除;C为单质,排除;而甲烷中只有极性键,排除D;故答案为A:分子中含有两个极性键、一个非极性键,属于共价化合物

完形填空

根据下面短文内容,在短文的空格处填上一个恰当的词,使短文完整、通顺。

Do you often like to use disposable (一次性的) chopsticks when   小题1: in restaurants? It’s time to drop this habit.

China produces 80 billion pairs of disposable chopsticks every year. “This is enough to cover Tian’anmen Square 363 times,” said Bai Guangxin, chairman of Jilin Forest Industry Group.

“The production of such chopsticks is a heavy burden (负担) on national forests,” Bai added. People need to cut     小题2: over 20 million 20-year-old trees to make way for this production.

Many people choose to use disposable chopsticks     小题3:  they think that they are cleaner. However, many disposable chopsticks are not as     小题4:  as people think. Some may even be toxic (有毒的), China Daily reported.

Several days ago, actor Huang Bo posted a message on his micro blog. He wrote that when he tried to wash the disposable chopsticks in a restaurant, he was     小题5: to find that the chopsticks turned the water yellow and gave off a bad smell.

Some scientists said the color and     小题6:  of the chopsticks may show that they have something harmful such as sulphur (硫磺) and other chemicals (化学品). That’s bad    小题7:    people’s health.

As Bai Guangxin suggested, it’s better that people carry their own chopsticks around. It doesn’t just help save the environment; it also   小题8:  our own health.

填空题