问题 问答题 简答题

为什么高山冷,而平地热?

答案

参考答案:

高山与平地冷热的差别,与太阳距离无关。由于地面吸收太阳光再辐射到空中后,才能使空气增温。在低层大气中,越靠近地面处,白天的气温升得越高,离地面越远,气温就越低。一般,平均海拔每升高100米,气温约降低0.6℃。由于高山高,空气较稀薄,增热少,风又比地面大,热量容易散失,所以高山冷,平地热。

阅读理解

Every time you go to the supermarket you come away with your purchases packed in plastic bags. But wouldn’t it be kinder to the environment if you asked for paper bags instead?

The answer is not as easy as it might seem. Environmentalists say there are drawbacks to using both plastic bags and paper bags.

80 percent of groceries in the US are packed in plastic bags and the numbers are becoming huge. Consumers use between 500 billion and 1 trillion plastic bags per year worldwide.

Some experts believe that all these bags harm the environment. Plastic takes hundreds of years to break down and, as it does so, poisonous materials are released into the water and soil.

Further damage is caused if plastic bags enter the sea. For example, endangered sea turtles cannot tell the bags from jellyfish, their main source of food, and often choke on them.

However, this kind of bag does have its advantages.

Paper bags use more energy and create more waste than plastic bags. Plastic bags require 40 percent less energy to produce and cause 70 percent less air pollution. They also release as much as 94 percent less waste into the water than paper ones do.

But paper bags do break down more quickly than plastic bags. They don’t endanger wildlife, either.

So what should we do? One possible solution would be to use biodegradable plastic bags. “Biodegradable” means that the bags break down naturally just like a piece of banana peel when it is left outside.

But until biodegradable technology improves, it might be easier to pack things you buy in reusable cloth bags.

小题1:Compared to paper bags, plastic bags ______.

A.produce 6 percent more waste

B.can be made biodegradable more easily

C.can be used as a source of food

D.save 40 percent of the energy小题2:By saying “The answer is not as easy as it might seem,” (in paragraph 2) the writer means _____.

A. biodegradable plastic bags can compete with paper

B. paper bags seem to be kind to environment

C. it’s difficult to say whether plastic or paper bags are better for the environment

小题3:What does the author suggest people use at the present time?

A.Paper bags

B.Plastic bags

C.Biodegradable plastic bags.

D.Cloth bags.

单项选择题