题干

以淀粉为基本原料可制备许多物质,如:

下列有关说法中正确的是(    )

A:淀粉是糖类物质,有甜味,与纤维素互为同分异构体

B:反应③是消去反应、反应④是加聚反应、反应⑤是取代反应

C:乙烯、聚乙烯分子中均含有碳碳双键,均可被酸性KMnO4溶液氧化

D:在加热条件下,可用银氨溶液将鉴别葡萄糖和乙醇

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答案(点此获取答案解析)

D

同类题2

根据短文内容,完成下面的表格。

      In common with other countries, Britain has serious environmental problems. In 1952, more than 4,000 people died in London because of the smog. The government introduced new laws to stop smog from coal fires and factories and the situation improved a lot.

      Today, London is much cleaner but there is a new problem: smog from cars. In December 1991, there was very little wind in London and pollution increased a lot. As a result, about 160 people died from pollution in just four days.

      One of the problem is the new "out of town" shopping centres. In the past, people often walked to shops near their homes or went by bus. Now, many people drive to the new shopping centres. Because the small shops have disappeared in the downtown, more people have to travel to do their shopping.

      Critics say that Britain needs better and cheaper public transport. Transport in Britain is very expensive. An early morning train trip from Glasgow to London (about 600km) can cost about £100, for example. A short 15-minute bus trip can cost over £1.00.

      Many people are trying to reduce the use of cars in Britain. Some cities now have special bicycle paths and many people cycle to work. Some people also travel to work together in one car to reduce the pollution and the cost.

Environmental ____ in Britain

Time

causes

____

Solutions

In the ____

Smog ____ coal fires and factories

____ 4,000 people died in 1952.

New laws were ____.

Today

Smog caused by ____.

About 160 people ____ in a few days in 1991.

★Provide better and ____ public transport.

★Build special paths for bicycles.

★Travel to work ____ in one car.