从性质上看，ETF联接基金可以看作是一种( )。A．保本基金 B．指数型基金 C．

合并有呼吸系统疾病患者术后护理的原则是（）。

A.维持循环稳定

B.保持呼吸道通畅

C.鼓励咳嗽、防止肺部感染

D.保持电解质和酸碱平衡

E.以上都是

HDV与DV的最大区别就在于其对高清晰度的支持。( )

上等初烤烟堆垛高度一般不大于（）个烟包。

A、4

B、5

C、6

D、7

Jazz was originally sung or played by the African slaves in America. In the 18th and 19th centuries, Africans were sold in America as slaves to work in large plantations（种植园）. After a hard day’s work, these people would gather together and sing, both to forget their worries and also to teach their children about the land and culture they came from. Early jazz music was basically the soulful and sad composition performed by black musicians who had little or no training in western music.

Many different kinds of music helped to create jazz. Jazz probably had its roots in the 19th century. African Americans created blues music from church music and sad songs from the times of slavery. In large cities, African Americans mixed these songs with music from other immigrants and then formed jazz. Sounds from West African, Spanish, French and even Arabic cultures can be heard in jazz music. In this way, jazz is like American culture. Jazz brings many ideas together from around the world to make something new.

There are many different ideas about where the word “jazz” came from.Some experts think that the word just borrows ideas from many different languages. They think that people may have made up their own word to describe the excitement of hearing and playing a new kind of music. Others think that the word comes from the Arabic word jazb. Middle Eastern jazb music and jazz have similar sounds. Several musicians from the Middle East have come to America to study jazz. They mix traditional jazz sounds with music from their own countries. This kind of jazz is called “fusion” and it is one of the most popular forms of jazz in America today.

43. African slaves in the plantations played early “jazz” to _____.

A. earn some money

B. entertain their slave owners

C. develop a kind of soulful and sad music

D. forget worries and keep their land in mind

44. Some experts think that the word “jazz” is a word for people to ______.

A. pronounce the Arabic word “jazb”

B. form a new kind of culture

C. express their inner feeling

D. create a way to explain themselves

45.What can we infer from the passage?

A. By comparison, African Americans have the greatest talent in the world.

B. American culture is a mixture of different cultural and social patterns.

C. The native Americans started jazz music in the time of slavery.

D. The music was created by some professional musicians from Africa.

46. The title of the passage could be ____.

A. Basic Information of Jazz

B. The Features of Jazz Music

C. Different Forms of Jazz Music

D. The Prospect of Jazz Music

小东在玩“勇士大战”游戏，进入第二关时，界面出现四个选项。第一个是“选择任意选项都需要支付游戏币”，第二个选项是“选择本项后可以得到额外游戏奖励”，第三个选项是“选择本项游戏后游戏不会进行下去”，第四个选项是“选择某个选项不需要支付游戏币”。
如果四个选项中的陈述只有一句为真，则以下哪项一定为真

A．选择任意选项都需要支付游戏币
B．选择任意选项都不需要支付游戏币
C．选择第二个选项后可以得到额外游戏奖励
D．选择第三个选项后游戏能继续进行下去