being used during “ 4 ” stages of flight, 5 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 6 to enforce a total ban, given that many passengers want to work during flights.
The difficulty is 7 how electromagnetic fields might affect an aircraft’s computers. Experts know that portable device emit radiation which 8 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 systems in order to damage navigation 9 . As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too 10 .
A) definite
B) incidents
C) effects
D) remains
E) critical
F) particularly
G) reluctant
H) refreshing
I) portable
J) enormous
K) predicting
L) liberal
M) affects
N) equipment
O) loud
四、改错
Most people work to earn a living and they
produce goods and services. Goods are either
agricultural (like maize) or manufactured (like
cars). Services are such things like education, 1._________
medicine, and commerce. These people provide 2.__________
goods; some provide services. Other people provide
both goods or services. For example, in the same 3.__________
garage a man may buy a car or some service which
helps him maintain his car.
The work people do is called as economic 4.__________
activity. All economic activities taken together make
up the economic system of a town, a city, a country,
or the world. Such economic system is the sum-total 5.__________
of what people do and what they want. The work
people do either provides what they need or provides
the money with that they can buy essential 6.__________
commodities. Of course, most people hope to have
enough money to buy commodities and services which
are essential but which provide some particular 7. __________
personal satisfaction, such as toys for children, visits 8. __________
the cinema, and books.
The science of economics is basic upon the facts 9. __________
of our everyday lives. Economists study our everyday
lives and the general life of our communities in order
to understand the whole economic system of which we
are a part. They try to describe the facts of the
economy in which we live, and to explain how it
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