问题 不定项选择

小明同学在学习DIS实验后,设计了一个测物体瞬时速度的实验,在小车上固定挡光片,使挡光片的前端与车头齐平、将光电门传感器固定在轨道侧面,垫高轨道的一端。小明同学将小车从该端同一位置由静止释放,获得了如下几组实验数据。则以下表述正确的是

①四个挡光片中,挡光片I的宽度最小;

②四个挡光片中,挡光片Ⅳ的宽度最小;

③四次实验中,第一次实验测得的速度最接近小车车头到达光电门时的瞬时速度;

④四次实验中,第四次实验测得的速度最接近小车车头到达光电门时的瞬时速度。 

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A.①③

B.②③

C.①④

D.②④

答案

答案:D

阅读理解

D

To us it seems so natural to put up an umbrella to keep the water off when it rains.But actually the umbrella was not invented as protection against rain.Its first use was as a shade against the sun.

Nobody knows who first invented it, but the umbrella was used in very ancient times.Probably the Chinese were the earliest to use it in the eleventh century BC.We know that the umbrella was used in ancient Egypt and Babylon as a sunshade.And there was a strange thing connected with its use: it became a symbol of honor and authority.In the Far East in ancient times, the umbrella was allowed to be used only by royalty or by those in high offices.

In Europe, the Greeks were the earliest to use the umbrella as a sunshade.And the umbrella was allowed in common use in ancient Greece.But it is believed that the earliest persons in Europe to use the umbrella as protection against rain were the ancient Romans.

During the Middle Ages, the use of the umbrella practically disappeared.Then it appeared again in Italy in the late sixteenth century.And again, it was considered a symbol of power and authority.In around 1680, the umbrella appeared in France and later on in England.

By the eighteenth century, the umbrella was used against rain throughout most of Europe.Umbrellas have not changed much in style during all this time, though they have become  much lighter in weight.It wasn’t until the twentieth century that women’s umbrellas began to be made in a whole variety of colors.

小题1:The first use of umbrella was as ______________.

A.protection against rain

B.shade against the sun

C.a symbol of power and authority

D.a symbol of honor and authority小题2:In Europe, the umbrella was first used against rain ___________.

A.in Greece

B.in Rome

C.in England

D.in France小题3:From the text, we can infer that _________.

A.the umbrella changed much in style in the eighteenth century.

B.no one knows why the umbrella was used in very ancient times.

C.once ordinary people had no right to use umbrellas.

D.during the Middle Ages the umbrella was common in Europe.小题4:This passage talks mainly about ____________.

A.when and how the umbrella was invented.

B.why the umbrella was so popular in Europe.

C.the development of the umbrella.

D.the history and use of the umbrella.

判断题