题目内容
（请给出正确答案）
19 Radar is used to determine the characteristics of radiocarbon.
A Right
B Wrong
C Not mentioned
如果结果不匹配，请 联系老师 获取答案
更多“19 Radar is used to determine …”相关的问题
Radar is used to determine the characteristics of radiocarbon.
A．Right
B．Wrong
C．Not mentioned
To identify planes flying overhead, the U. S. air-traffic controllers used to _____.
A．get information by communication through phone calls
B．depended on the "war room" for information
C．collect data by way of radar
D．use several computers working at the same time
Radar (雷达)
1. Children enjoy shouting at a high wall and hearing the sound come back to them. These sounds are called echoes (回声). Echoes have given us a number of 'valuable tools.
2. Echo sounding devices were early used in making maps of the ocean floor. Sounds or Ultrasonic (超声的) sounds make good tools for determining how deep the water is under ships. Sometimes echoes from ultrasonic distance finding devices were prevented from working by fish swimming past or by the presence of large objects. So ultrasonic devices have been replaced by other tools.
3. Radar is now a familiar tool. Like many others it was ah unexpected discovery. It was first observed by two researchers, who were studying sound communication. They were sending signals from a station on one side of a river in Washington, D .C. to a vehicle across the river. They discovered that their signals were stopped by passing ships. They recognized the importance of this discovery at once.
4. All this was of course just a start, from which our present radar has developed. The word "radar," in fact, gets its name from the term "radio detection (检测) and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Today, in our scientific age, it would be difficult to manage without radar.
5. One of the many uses of radar is as a speed control device on highways. When a person in an automobile is driving faster than the speed limit, radar will show this clearly and the traffic police can take measures to stop him.
6. A pilot cannot fly a plane by sight alone. Many conditions such as flying at night and landing in dense fog require the pilot to use radar. Human eyes are not very good at determining speeds of approaching objects, but radar can show the pi lot how fast nearby planes are moving.
A Study of Sound
B Highway Police
C Working Principles
D Early Use of "Radar"
E Useful Tools
F Discovery by Chance
Paragraph 2 ______
19 Emotional memory is used when we perform. physical movements．
A Right B Wrong C Not mentioned
To get a full appreciation of what this means we must turn first to some recent human inventions. Everyoneknows that if he shouts near a wall or a mountainside, an echo will come back. The further off this solid obstacle, the longer time it will take for the return of the echo. A sound made by tapping on the main body of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps andthe receipt of the echoes the depth of the sea at that point can be calculated.So was born the echo-sounding equipment, now in general use in ships. Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step fromlocating the sea bottom to locating a shoal of fish. With experience, and with improved equipment, it is now possible not only to locate fish but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
A few years ago it was found that certain bats emit squeaks (吱吱声) and by receiving ’he echoes they could locate and steer clear of obstacles--or locate flying insects on which they feed.This echolocation in bats is often compared with radar, the principle of which is similar.@@@@@@@ Choose correct answers to the question:
The main purpose of this passage is to ______.
A.describe that animals can make different sounds
B.prove that animals’ voices can play practical roles
C.inspire the readers to make more inventions
D.startle the readers with some shocking facts
The discovery of echolocation may help with all of the following EXCEPTA.measuring the depth of the sea
B.distinguishing different kinds of fish
C.improving the functions of radar
D.varying the size and nature of an object
By saying "A shoal of fish will do this"(Lines 6-7, Para 2), the author means ________.A.only one special kind of fish can reflect sounds
B.only one special kind of fish can be used to help locate a ship
C.a large group of fish can reflect sounds
D.a large group of fish can be used to help locate a ship
As it is discussed in the passage, the squeaks of bats can be functionally compared with ________.A.human languages
B.a mountainside
C.a shoal of fish
D.taps on a ship
Which of the following statements can be inferred from the passage？A.Animals are more intelligent than humans.
B.Humans are more intelligent than animals.
C.Animals are often compared with human inventions.
D.Humans are often inspired by animals.
请帮忙给出每个问题的正确答案和分析，谢谢！
听力原文：Why don't I give you my accountant's number？
(A) I've used him for three years.
(B) No, I don't have an accountant.
(C) That would be very helpful.
(19)
A．
B．
C．
W: But people used to blame it on factories.
Q: What did we suppose to be responsible for the smog？
(19)
A．Factories.
B．Automobiles.
C．American cities.
D．Flames.
听力原文：W：It's so chilly and we have to wait for Bill．He always comes late．
M：He used to，but this evening，he won't.
Q：What does the man think bf Bill？
(19)
A．Bill is a punctual person.
B．Bill will come on time tonight.
C．Bill will be late as usual.
D．Bill won't come at all.
听力原文：W: Do you have a savings account at the bank？
M: I used to, but recently I withdrew all the money.
Q: Which of the following statements is TRUE for the man's money？
(19)
A．He lost his money.
B．He had an account with him.
C．He had no money in the bank.
D．He had spent all his money.
听力原文：W：It's so chilly and we have to wait for Bill．He always conies late．
M：He used to，but this evening，he won't．
Q：What does the man think of Bill？
(19)
A．Bill is a punctual person.
B．Bill will come on time tonight.
C．Bill will be late as usual.
D．Bill won't come at all.
