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A wind tunnel can be used to find out ________.
[A] how fast a plane can rise
[B] how smooth a plane’s surface is
[C] if a plane can land in a very strong wind
[D] if a plane will drop when flying at a low height
答案
更多“A wind tunnel can be used to find out ________.[A] how fast a plane can rise[B] how”相关的问题
第1题
EA wind tunnel (风洞) is used for teasing planes or plane models. In a wind tunnel air is blown over a plane or a model placed in a test section (区).Wind tunnel test sections are different in size depending on airflow speed requirements. Some low-speed tunnels have test sections large enough for a complete small plane. In the very high speed tunnels used for space testing, however, the model may be as small as a pencil.
There are two ways of feeding air to the test section. In the constant flow tunnel, airflow is produced by electric fans. It is forced through the tunnel to the test section, then through another tunnel section back to the starting point for reuse.
The other way involves (卷入) storing high-pressure air in a box, sending it out by a controlling device (装置) to pass through the tunnel and test section into another box. This way is usually used for a very short period of high-speed airflow.
Wind tunnels are usually used to test planes before they are flown. Problems in a plane can be found when it meets the high-speed airflow in the tunnel. For example, if the wings are built so that they would weaken (become weak) at high speeds, this fact can be discovered in the tunnel, saving many lives and millions of dollars.
In a wind tunnel, scientists also find out how different planes will act different speeds. They find out such things as how the air dives by the wing surfaces, how slowly a plane can fly before it starts to drop, and how fast it can climb.
第52题：Some wind tunnel sections are larger than others because ________.
[A] they are used large planes
[B] stronger wind can be produced in them
[C] they are built to meet a higher speed test
[D] the wind used in them flows at a lower speed
第2题
Why does the author suggest that the experiments with the wind tunnel were important？
A．Because they allowed the Wright brothers to decrease the weight of their airplane.
B．Because they resulted in a three-axis control for their airplane.
C．Because they were important in the refinement of the wings for their airplane.
D．Because they used the data to improve the engine for their airplane.
第3题
第4题
A．It runs on a monorail.
B．It can move on a monorail suspended from the roof of the tunnel.
C．It is in position in the middle of the tunnel,
D．It can take quick action.
第5题
One of the problems with wind farms is that ______
A．there is not enough wind
B．wind is not reliable.
C．they can only be built on the sea
D．they might influence the world economy.
第6题
Weather stations can not only tell us about wind speed, but also about rainfall.
A．Y
B．N
C．NG
第7题
According to the last paragraph, what are the advantages of wind power technology？
A．It can be used for different purposes.
B．It can replace nuclear power plant.
C．It can be installed in one's backyard.
D．Both A and Ｃ.
第8题
听力原文：Why can the Robogat quickly get through to the scene of a fife？
(35)
A．It runs on a monorail.
B．It can move on a monorail suspended from the roof of the tunnel.
C．It is in position in the middle of the tunnel,
D．It can take quick action.
第9题
The trumpet of a prophecy "0 Wind/If winter comes, can spring be far behind？" is from
A．Keats" Ode to a Nightingale.
B．Byron"s The Isles of Greece.
C．Shelly"s Ode to the West Wind.
D．Frost"s Stopping by Woods on a Snowy Evening.
第10题
One of the problems with wind farms is that
A．there is not enough wind.
B．wind is not reliable.
C．they can only be built on the sea.
D．they might influence the world economy.
