题干

土豆切开以后进行处理,具体实验情况如下:

编号

块状土豆处理方法

5分钟后块茎表面

4小时后块茎表面

浸入水中

不变色

不发黑

用热水烫过

很少呈现浅紫红色

很少发黑色

不作任何处理

有浅紫红色

发黑

放入氧气中

明显呈浅紫红色

深度发黑

根据此实验提出的下列推测中,不合理的是(  )

A:若用水处理块状土豆,此块茎就不会发黑

B:块状土豆中存在某种活性物质

C:若隔离空气,土豆块茎中的某种物质不会变化而产生黑色新物质

D:若对土豆块茎经开水处理,可能使土豆中某种物质减少

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答案(点此获取答案解析)

A

同类题2

信息归纳

    With the rapid development of science and technology, communication methods of people have changed a lot in the past years. As we all know, in ancient times, people communicated with people who were far from them only by letters, which took a very long time to get the message.

    In the 19th century, telegraph (电报) was invented, but it was not widely used, letter is still the main method at that time. In 1836, John Coker invented the first electromagnetic telegraph(电磁电报机) in the world, then telegraph came into being and was popular, which was much faster than letter, bringing great convenient to people.

    As time goes by, telephones become increasingly widely used. Now, the phone has been developed as mobile phone, fixed telephone, Internet telephone and other categories, being an essential communication tool in modern information society.

    In addition, network communication is popular as well. It is especially widely welcomed by the youths. A great number of people communicate with others on the Internet by using software, such as email, QQ, WeChat, bbs, MSN and so on. Using software is easy. A computer which is connected to the network is enough. In China, WeChat has become the most popular communication software nowadays. WeChat, known as Weixin in China, is a mobile phone text and voice messaging communication software which is developed by Tencent. People can make video calls that not only can hear the sound, but also can see the people you talk to.

Information Card

The method of communication in ancient time

____

The time when the telegraph was invented

____

The person who invented the electromagnetic telegraph

____

The software which has become the most popular in China

____

The number of the communication methods which are mentioned

____