题干

下列关于癌细胞的叙述,错误的是(    )

A:癌细胞是正常细胞发生突变而形成的

B:癌细胞容易转移是因为其表面的粘连蛋白很少或缺失

C:癌细胞具有无限增殖的能力

D:癌细胞是由于细胞直接分化而来

上一题 下一题 0.0难度 选择题 更新时间:2016-08-04 12:16:57

答案(点此获取答案解析)

D

同类题3

阅读理解

    Zhalong is a nature reserve in Heilongjiang in northeast China.It is one of the world's most important wetlands.The area provides food and shelter for wildlife.It is an ideal home for different kinds of plants,fish and birds.

    Many birds live comfortably in Zhalong Nature Reserve all year round,while some only stay for a short time.There are many fish in the wetlands,and the birds can easily catch them for food.Zhalong Nature Reserve is an important living area for the rare red-crowned cranes.There are not manyred-crowned cranes in the world.Some of them live in Zhalong.

    Some people want to change the wetlands to make more space for farms and buildings.This means that there will be less and less space for wildlife.

    More and more birds are in danger because they do not have enough living space.Many of them died.The Chinese government wants to protect these endangered birds,and they can be safe in Zhalong.

    Every year a lot of tourists go to Zhalong to watch birds.This year members of ourBird watching Club are going to study the different kinds of birds in Zhalongand the changes in their numbers.The study begins next month.

    We do a bird count once a year.We are now inviting secondary school students to help.We need more people to help us count and do something to help the birds.Many people do not understand the importance of the wetlands.We hope this information will help them understand and make them actively take action to protect wildlife.

同类题5

    阅读下面短文,从每小题所给的A、B、C、D四个选项中选出最佳选项。

A

    A taxi company in one of Japan's big cities is introducing silent taxi drivers.Miyako Taxi,which is based in Kyoto,showed the new idea in March.The business is recently operating five "Silent Taxis" across the city.

    The cars look like any ordinary taxi,but a notice written on the back of the passenger seat tells passengers that they have entered one of the new silent cars.Drivers will offer a greeting when their passenger enters the car,and after making sure the route(路线)they will not start small talks.The drivers are only allowed to take their part in a conversation,only if they are spoken to first.Of course,they are also allowed to communicate in emergency(紧急的) situations.

    While introducing the idea to the public,a spokesman from Miyako Taxi said,"This service is currently in a trial(试验)period.It is introduced in order to create an in-car environment that provides the most comfortable ride for our passengers through reducing the driver's speaking."

    According to reporters from Japan Today,an online newspaper based in Tokyo,the taxi company made the decision after hearing reports from passengers that they felt bored to be forced to chat with their drivers.

    At the end of the trial period,the company will see how popular the silent taxis are with passengers before deciding whether to roll it out across more of their drivers or not.