美国数据加密标准(DES)属于( )。A．单钥加密体制 B．双钥加密体制 C．单钥加

下述大脑皮质对呼吸运动调节的描述，哪个是不正确的

A．言语与歌唱反映了大脑皮质对呼吸的控制作用
B．大脑皮质通过控制低位脑干呼吸神经元调节呼吸
C．对呼吸运动的随意控制必须依赖于大脑皮质
D．在人类平时生活中，呼吸对环境的适应并不需要大脑皮质参与

China is a land of bicycles.At least it was back in 1992 when I traveled the country.Back then everyone seemed to be riding a bicycle.Millions of them，all black.Cars were rare.Yet since my arrival in Beijing last year，I’ve found the opposite is true.There are millions of cars.However，people still use their bicycles to get around.For many，it’s the easiest and cheapest way to travel today.Bicycles also come in different colors－silver，green，red，blue，yellow，whatever you want.

It’s fun watching people biking.They rush quickly through crossroads，move skillfully through traffic，and ride even on sidewalks(人行道)．Bicycles allow people the freedom to move about that cars just can’t provide.

Eager to be part of this aspect of Chinese culture，I decided to buy a bicycle.Great weather accompanied my great buy.I immediately jumped up on my bicycle seat and started home.

My first ride home was orderly (守秩序的)．To be safe，I stayed with a“pack”of bikers while cars on the streets came running swiftly out of nowhere at times.I didn’t want to get hit.So I took the ride carefully.

Crossing the streets was the biggest problem.It was a lot like crossing a major highway back in the United States.The streets here were wide，so crossing took time，skill and a little bit of luck.

I finally made it home.The feeling on the bicycle was amazing.The air hitting my face and going through my hair was wonderful.I was sitting on top of the world as I passed by places and people.Biking made me feel alive.

小题1:According to the author，why are bicycles still popular in China today?

A．Because they are traditional and safe.

B．Because they are convenient and inexpensive.

C．Because they are colorful and available.

D．Because they are fast and environment friendly.小题2:The author decided to buy a bicycle because he intended ________.

A．to ride it for fun

B．to use it for transport

C．to experience local culture

D．to improve his riding skills小题3:How did the author feel about his street crossing?

A．It was boring.

B．It was difficult.

C．It was lively.

D．It was wonderful.小题4:Which of the following best describes the author’s biking experience?

A．The author enjoyed showing off his biking skills.

B．The author was annoyed by the air while riding.

C．The author was praised by the other bikers.

D．The author took great pleasure in biking.

为了体现公平竞争和便于招标人选择综合能力最强的投标人中标，在邀请招标时，仍要求在投标书内报送表明投标人资质能力的有关证明材料，通常称为( )。

A．资格预审

B．资格审查

C．资格后审

D．资格核查

中英联合联络小组今天在香港举行的21次防务与治安问题专家会议，继续讨论关于中国人民解放军的少数人员提前进港做好各项准备工作的问题。尽管双方对于中国人民解放军少数先遣人员提前进港做好各方面的准备工作达成共识，但对于具体的安排，中英双方还要进行具体的讨论。
这段话主要支持了这样一个论点，即( )。

A．人民解放军将是入港的先遣队

B．中英双方已就解放军先遣人员提前进港达成一定的共识

C．事实上中英双方对于先遣人员的具体问题并未取得一致意见

D．中英联合联络小组举行专家会议，讨论解放军先遣人员提前进港问题

管理信息系统的学科特点是什么？