问题 多选题

有一交变电流如图所示,则由此图象可知(  )

A.它的周期是0.8s

B.它的峰值是4A

C.它的有效值是2

2
A

D.它的频率是0.8Hz

答案

A、由此图象可知它的周期是0.8s,故A正确;

B、它的峰值是4A,故B正确;

C、它不是正弦式电流,因此有效值不是等于最大值除以根号2,即它的有效值不是2

2
A,故C错误;

D、它的周期是0.8s,频率f=

1
T
=1.25Hz,故D错误;

故选:AB.

阅读理解

Although English is not as old as Chinese, it is spoken by many people around the world every day. English speakers are always making up new words, and we are often able to know where most come from.

Sometimes, however, no one may really know where a word comes from. Did you ever think about why hamburgers are called “hamburgers”, especially when they are not made with ham(火腿)? About a hundred years ago, some men went to America from Europe. They came from a big city in Germany called Hamburg. They didn’t speak good English, but they ate good food. When some Americans saw them eating round pieces of beef, they asked the Germans what they were. The Germans didn’t understand the question and answered, “We come from Hamburg.” One of these Americans owned a restaurant, and had an idea. He cooked some round pieces of bread with beef in them and started selling them. Such bread came to be called “hamburgers”. Today, “Hamburgers” are sold in many countries around the world.

Whether this story is true or not, it certainly is interesting. Knowing why any word has a certain meaning is interesting, too. This reason, for most English words, can be found in any large English dictionary.

小题1:English is spoken by many people around the world every day, but English is ______.

A.as old as Chinese

B.older than Chinese

C.younger than Chinese

D.older than German小题2:Hamburg is ______.

A.a kind of food

B.a round piece of beef

C.the name of a country

D.a city in Germany小题3:According to the story, the word “hamburger” comes from ______.

A.English speakers because they’re always making up new words

B.the round piece of beef which those people from Hamburg ate

C.English because Germans don’t speak good English

D.a large English dictionary小题4:. Which of the following is TRUE?

A.Few Americans like hamburgers.

B.Hamburgers are made with ham.

C.Hamburgers were first sold a century ago.

D.Hamburgers were some people.小题5:. Which of the following can be found in any large dictionary?

A.Where Germans came from.

B.Where all the new words came from.

C.The reason why a new word has a certain meaning.

D.Why English is spoken all over the world.

单项选择题 A1/A2型题