下列物质按熔沸点由高到低排列的是

A．NaCl SiO₂ CO₂ Na　

B．HI HBr HCl HF　　　

C．NaCl KCl KBr KI

D．P₄ N₂ Br₂ O₂

读写任务（共1小题，满分25分）

阅读下面的短文，然后按照要求写一篇150左右的英语短文。 

Mankind is wasting things everywhere and everyday . Wherever we go , we can see that food is wasted just because of poor taste ; clothes are thrown away simply due to their old fashion . Trees are cut down merely for fuel ; wild animals are killed simply for meat and fur ; oil and coal are exploited (开采) in a bad way .

The worst example of man’s waste is the waste of time . Many people tend to spend their time on worthless things , such as wandering about in the street , gossiping（闲聊） in the office , sleeping too much during the day .

It is time to call for an end to the waste . On one hand , we must save on natural resources and make full use of them . On the other hand , we must value time .

[写作内容]

(1) 以约30个词概括短文的要点；

(2) 然后以约120个词就“珍惜时间”的主题发表你的看法，至少包含以下的内容要点：

①简要论述为什么要珍惜时间。

②结合自身实际谈谈我们学生应该如何珍惜时间。

[写作要求]

(1) 可以使用实例或其它论述方法支持你的论点，也可以参照阅读材料的内容，但不得直接引用原文中的句子；

(2) 标题自定。

[评分标准]

        概括准确，语言规范，内容合适，篇章连贯。