题目内容
with the portable computer in business class. In the last 15 years, pilots have reported well over
100 incidents that could have been caused by electromagnetic interference. The source of this
interference remains unconfirmed, but increasingly, experts are pointing the blame at portable
electronic devices such as portable computers, radio and cassette players and mobile telephones.
RTCA, an organization which advises the av
airlines ban such devices from being used during "critical" stages of flight, particularly take-off
and landing. Some experts have gone further, calling for a total ban during all flights. Currently,
rules on using these devices are left up to individual airlines. And although some airlines prohibit
passengers from using such equipment during take-off and landing, most are reluctant to enforce
a total ban, given that many passengers want to work during flights.
The difficulty is predicting how electromagnetic fields might affect an aircraft's computers.
Experts know that portable devices emit radiation which affects those wavelengths which
aircraft use for navigation and communication. But, because they have not been able to reproduce
these effects in a laboratory, they have no way of knowing whether the interference might be
dangerous or not.
The fact that aircraft may be vulnerable (易受损的) to interference raises the risk that
terrorists may use radio system in order to damage navigation equipment. As worrying, though,
is the passenger who can't hear the instructions to turn off his radio because the music's too loud.
B. the defects of electronic crashes
C. a possible cause of aircraft crashes
D. effective safety measures for air flight
B. They may have taken place during take off and landing.
C. They were proved to have been caused by the passengers' portable computers.
D. They were suspected to have resulted from electromagnetic interference.
B. the harmful effect of
C. most passengers refuse to take a plane which bans the use of radio and cassette players.
D. they have other effective safety measures to fall back on.
computers?______
B. Because it remains a mystery what wavelengths are liable to be interfered with.
C. Because research scientists have not been to produce the same effects in labs.
D. Because experts lack adequate equipment to do such research.
B. has overestimated the danger of electromagnetic interference
C. hasn't formed his own opinion on this
D. regards it as unreasonable to exercise a total ban during flight
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 阅读理解. | ||||||||||||
| Advertising is a form of communication that uses all kinds of media, and is visible everywhere these days. Typical customers of advertising companies are other companies, or businessmen, who want to persuade potential customers to buy more of what they make or sell. But there are other kinds of customers. Some organizations spend large sums of money on advertising a political party or other group that sells what is not, strictly speaking, a product or service. Such non - profit organizations are not typical advertising customers, and they prefer ways of spreading knowledge, changing attitudes, and improving society. Many advertisements are designed to increase sales of products and services by either improving brand image or, in the case of non - profit organizations, expressing ideas. In order to achieve th~s, advertisements will often pass on truthful information while delivering their messages. Every major medium is a means of delivering these messages, including television, radio, cinema, magazines, newspapers, video games, the Internet and billboards (大幅广告牌). Advertising will usually be created and. placed by an advertising agency on behalf of company or other organization. Spending on advertising has increased greatly in recent years. In 2006, spending was estimated at $155 billion in the United States and $385 billion worldwide; the latter is expected to reach more than $500 billion by 2010. While advertising can be seen as a necessity for economic growth and social development, it is not without social costs. Advertisement emails and other forms of junk mail have become so popular that ~they have become a major burden to users of I nternet email services, as well as a financial burden on Internet email service providers.
| ||||||||||||