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A.whereas
B.moreover
C.furthermore
D.somehow
答案
更多“Proper lightening is necessary for good eyesight, ________ human night vision can be ”相关的问题
第2题
One form. of lightening that ........ is ball lightening.
第3题
A. occurs most infrequently
B. is shifted sideways by strong winds
C. is often hidden from our view
D. is equipped with a good knowledge of various forms of lightening
E. is estimated at 20 millions a year
F. is positively charged
In most cases of cloud-to-ground lightening, the ground's surface ______.
第5题
The American Space Agency ______ (delay)the launch of the Shuttle Endeavour while it tries to find out what damage ______ (do)by 11 lightening strikes around the launch pad at Cape Canaveral.
第6题
A．Me advocates keeping students motivation and lightening their study burden.
B．He encourages teachers to cram (填鸭式地教育) more to their students.
C．He will place more emphasis on continuous assessment throughout the year and on project and assignment work.
D．None of the above.
第7题
No one knows for sure just how old kites are。 In fact， they have been in use for centuries。 25 centuries ago， kites were well-known in China。 These first kites were probably made of wood。 They may even have been covered with silk， because silk were used a lot at that time。 Early kites were built for certain uses。 In ancient China， they will use to carry ropes to cross rivers。 Once across， the ropes were tear down and wooden bridges would hang for them。 Legend tells of one General who flew musical kites over the enemies’ camp。 The enemy fled， believing the sounds to be the warming voices of angels。 By the 15th century， many people flew kites in Europe。 Marco Polo may have brought the kite back from his visit to China。 The kite has been linked to great names and events。 For instance， Benjamin Franklin used kite to prove the lightening electricity。 He flew the kite in the storm。 He did this in order to draw lightening from the clouds。 He tied a metal key and a strip of silk to the kite line。 The silk ribbon would stop the lightening from passing through his body。 Benjamin’s idea was first laughed at。 But later on， it enlightened the invention of the lightening rod。 With such grand history， kite flying is short remain an entertaining and popular sport。
Question 16 to 18 are based on the passage you have just heard。
Question 16： What does the speaker say about kite？
Question 17： What did ancient Chinese use cats to do？
Question 18： Why did BF flied a kite in the storm？
第8题
What is the impact hypothesis？
A．The theory that the continents drifted and collided with each other
B．The idea that volcanic eruptions disrupted the climate worldwide
C．The view that a lightening storm caused a global fire
D．The premise that an asteroid crashed, blocking the sunlight on Earth
第9题
No one knows for sure just how old kites are. In fact, they have been in use for centuries. 25 centuries ago, kites were well-known in China. These first kites were probably made of wood. They may even have been covered with silk, because silk was used a lot at that time.
Early kites were built for certain uses. In ancient China, they were used to carry ropes across rivers. Once across, the ropes were tied down and wooden bridges were hung from them. Legend tales of one general who flew musical kites over the enemy’s camp. The enemy fled, believing the sounds to be the warning voices of angels. By the 15th centuries, many people flew kites in Europe. Marco Polo may have brought the kite back from his visit to China. The kite has been linked to great names and events. For instance, Benjamin Franklin used the kite to prove that lightening is electricity. He flew the kite in a storm. He did this in order to draw lightening from the clouds. He tied a metal key and a strip of silk to the kite line. The silk ribbon would stop the lightening from passing through his body. Benjamin’s idea was first laughed at, but later on it led to the invention of the lightening rod.
With such grand history, kite flying is sure to remain an entertaining and popular sport.
Q: What does the speaker say about kites？
A.No one knows exactly where they were.
B.No one knows for sure when they came into being.
C.No one knows for what purpose they were.
D.No one knows what they will.
第10题
Volts from the Sky
Lightning has caused awe and wonder since old times. Although Benjamin Franklin demonstrated lightning as an enormous electrical discharge more than 200 years ago, many puzzles still surround this powerful phenomenon.
Lightning is generated when electrical charges separate in rain clouds, though processes'are still not fully understood. Typically, positive charges build at the cloud top, while the bottom becomes negatively charged. In most instances of cloud-to-ground lightning, the negatively charged lower portion of the cloud repels negatively charged particles on the ground's surfaces, making it become positively charged. The positive charge on the ground gathers at elevated points.
A flow of electrons begins between the cloud and earth. When the voltage charge becomes large enough, it breaks through the insulating barrier of air, and electrons zigzag earthward. We see the discharge as lightning.
Lightning can occur within a cloud, between clouds, or between clouds and the ground. The first variety, intra-cloud lightning, is the most frequent but is often hidden from our view. Cloud-to-ground lightning, making up about 20 percent of lightning discharges, is what we usually see. Lightning comes in several forms, including sheet, ribbon, and ball. Intra-cloud lightning can illuminate a cloud so it looks like a white sheet, hence its name. When cloud-to-ground lightning occurs during strong winds, they can shift the lightning channel sideways, so it looks like a ribbon. The average lightning strike is more than 3 miles long and can travel at a tenth of the speed of light. Ball lightning, the rarest and most mysterious form, derives its name from the small luminous ball
that appears near the impact point, moves horizontally, and lasts for several seconds.
Thunder is generated by the tremendous heat released in a lightning discharge. Temperatures near the discharge can reach as high as 50,000F within thousandths of a second. This sudden heating acts as an explosion, generating shock waves we hear as thunder.
About 2,000 thunderstorms are occurring in the world at any time, generating about 100 lightning strikes every second, or 8 million daily. Within the United States, lightning strikes are estimated at 20 million a year, or about 22,000 per day. You have a 1-in-600,000 chance of being struck by lightning during your lifetime. Lightning can strike twice or more in the same spot. The Empire State Building in New York is struck by lightning about two dozen times annually.
You can measure how far you are from a lightning strike by counting the seconds between viewing the flash and hearing the bang, and then dividing by five. This approximates the mileage.
A. Cloud-to-ground lightening occurring in the US
B. Types of lightening
C. Cause of lightening
D. Differences between thunder and thunderstorm
E. Frequencies of thunderstorms occurring in the world and the US
Paragraphs 2 and 3 ______.
