计算机内部用几个字节存放一个7位ASCII码A．1 B．2 C．3 D．4

Rivers are one of our most important natural resources(资源). Many of the world’s great cities are located on rivers, and almost every country has at least one river running through it that plays an important part in the lives of its people.

Since the beginning of history, people have used rivers for transportation. The longest one in the United States is the Mississippi. The lifeline of Egypt is the Nile. To the people of India, the Ganges is great, but it is also important for transportation; ships can travel along it for a thousand miles. Other great rivers are the Congo in Africa and the Mekong in southeastern Asia. The greatest of all for navigation（航海）, however, is the Amazon in Brazil（巴西）. It is so wide and so deep that large ships can go about two thousand miles up it.

Besides transportation, rivers give food to eat, water to drink, water for crops, and chances for fun. In order to increase the supply(供给) of water for crops, engineers sometimes build a dam (大坝)across a river and let a lake form behind the dam. Then people can use the water not only to irrigate(灌溉) their fields but also to make electricity for their homes and industries.

However, large cities and industries that are located on rivers often cause problems. As the cities grow in size and industries increase in number, the water in the rivers becomes polluted with chemicals and other materials. People are learning the importance, however, of doing more to keep their rivers clean if they want to enjoy the benefits of these natural resources.

小题1:The greatest river for navigation is ________________.

A．the Mississippi

B．the Nile

C．the Mekong

D．the Amazon小题2:Which is NOT true according to the passage?

A．Many cities are located on rivers.

B．Almost every country has at least one important river.

C．The Nile is in India.

D．Rivers play an important part in the lives of people.小题3:When rivers are dammed, people use the water for __________.

A．keeping the rivers clean

B．making electricity

C．washing clothes

D．irrigation and the production of electricity小题4:Most water in rivers is polluted with ___________.

A．people’s drinking water too much

B．people’s swimming in the river too much

C．chemicals and other materials

D．people’s building a dam across a river小题5:The best title for the passage is _____________.

A．The Importance of Rivers

B．Rivers in Cities

C．Transportation

D．Natural Resources

--- Why do you suggest we buy a new machine?

--- Because the old one has been damaged ___________.

A．beyond reach

B．beyond repair

C．beyond control

D．beyond description

近年来，“晒客”一词窜红网络。晒工资、晒消费、晒工作、晒宝宝……时下的“晒”成了公众的常用词，特别是人们越来越多地“晒”政治，“晒”也成为了社会的政治生活形态。“晒”政治表明（    ）

①我国政治生活民主化程度不断提高   ②公民行使监督权，推进社会主义民主政治建设 

③公民享有管理国家事务的权利        ④公民是国家的主人，是国家权力的主体

A．①②③

B．②③④

C．①③④

D．①②④

B型胃炎常有以下特点()

A．有血清壁细胞抗体

B．病变在胃窦黏膜

C．常伴恶性贫血

D．部分可发生癌变

E．有内因子抗体

体表血络扩张，纵横丛集形成的肿瘤是（）

A.气瘤

B.血瘤

C.筋瘤

D.肉瘤

E.骨瘤