Text 1

Source A:
In many criminal cases, police may have a good idea of who committed the crime, but they lack
witnesses to the crime. If there are no witnesses, and the police are unable to obtain a
confession from a suspect, they may be unable to convict that person in a court of law. In such
situations, lie detector machines can play a valuable role.
Lie detector machines work by measuring the pulse, blood pressure, and other bodily functions
of an individual. When a person lies, there are noticeable changes in these bodily functions,
such as increases in pulse and blood pressure. Since these reactions are involuntary, they are
impossible to hide and clearly indicate when a person is lying.
Also, the lie detector is an ideal tool for law enforcement. The usefulness of lie detector
machines is already widely recognized in the American court system. The results of lie detector
tests have been used to obtain convictions in a number of cases where there were no witnesses
to the crime.
Another benefit of lie detector machines is that they are cheap, and the technology to produce
them is readily available. Lie detectors are made from components that are widely used in the
medical industry. It would be a relatively simple and inexpensive process to equip every police
station with a lie detector
machine in the near future.
Source B:
TV shows may have scenes where a crime is solved with the help of a lie detector machine.
While this is common on screen, in reality, these machines are not as useful as many people
believe them to be.
First, lie detector machines rely on changes in things like pulse to detect when a person is lying.
While these changes are involuntary, they do not necessarily mean a person is lying. The same
changes occur when a person is frightened or very nervous, which is often the case when a
person takes a lie detector test, even if he is telling the truth. So it is not uncommon for people
to tell the truth and still fail a lie detector test.
Second, while lie detector tests have been used with success in the American court system,
they are being used less and less. Across the nation, law enforcement agencies are beginning to
realize that lie detector machines might not be an accurate or useful tool.
Finally, while lie detector machines themselves are cheap and readily available, they must be
operated by highly trained individuals. There are special techniques that must be used for lie
detectors to be effective, and questions must be asked in a certain way. Training in the proper
use of lie detector machines is long and time-consuming, and there is a serious lack of qualified
people to operate them.
Text 2
Source A:
Traditionally, most surveys have been conducted via telephone or post mail. In the 21st
century, however, online surveys have emerged as a promising alternative because online
surveys hold several advantages.
First, online surveys are much less cumbersome to administer and analyze. Traditional survey
methods require significant manpower investments. A survey team is needed to either place
the telephone class or mail the surveys to consumers. In comparison, very little manpower is
needed to distribute an online survey, as the computer can be programmed to do this
automatically. Furthermore, the responses to online surveys are simply submitted to a
webpage, further simplifying the process.
Online surveys also lead to an increased response rate. Since online surveys can reach a far
greater number of people than a traditional survey can, they naturally result in a higher number
of responses. Also, responding to an online survey requires very little effort on the part of a
consumer, increasing the likelihood that he or she will participate in it.
Finally, online surveys allow marketers to reach a wider range of individuals than would be
possible through traditional survey techniques. Reaching people of different ages, cultures, and
classes is essential because it gives marketers a view of every possible opinion. Since Internet
access is nearly universal, online surveys virtually guarantee that a survey will reach every
possible group.
Source B
The Internet has become the preferred platform for conducting surveys. At first glance it may
seem like the Internet offers a number of advantages for groups wishing to conduct surveys,
but there really are a few disadvantages.
One major disadvantage of online surveys is that they actually take a lot of manpower. Survey
conductors need a group of people to write the survey program, and even a larger group of
people to maintain the website where the responses are submitted. However, online survey
websites are a favorite target of computer hackers, so it takes a considerable allocation of
manpower to protect the website and keep it running.
Getting a sufficient number of responses to an online survey can also be a problem. When the
participants go to a website and are asked to take a survey before entering the site, they do not
actually take the survey. Instead, they click past it and go to the website. In fact, studies show
that the vast majority of Internet users do not respond to surveys in these situations.
Finally, online surveys are often inaccurate. The online community is not really an accurate
reflection of society. There are large portions of the population that do not use the Internet. For
example, 72% of 24-year-olds regularly access the Internet, but only about 23% of 65-year-olds
do so. That means that the elderly are not accurately represented in online surveys. A similar
trend can be seen in regard to class, with fewer poor people having Internet access than
wealthier individuals.
Car manufacturers and governments have been eagerly seeking a replacement for the
automobile's main source of power, the internal-combustion engine. By far the most promising
alternative source of energy for cars is the hydrogen-based fuel-cell engine, which uses
hydrogen to create electricity that, in turn, powers the car. Fuel-cell engines have several
advantages over internal-combustion engines and will probably soon replace them.
One of the main problems with the internal-combustion engine is that it relies on petroleum,
either in the form of gasoline or diesel fuel. Petroleum is a finite resource; someday, we will run
out of oil. The hydrogen needed for fuel-cell engines cannot easily be depleted. Hydrogen can
be derived from various plentiful sources, including natural gas and even water. The fact that
fuel-cell engines utilize easily available, renewable resources makes them particularly attractive.
Second, hydrogen-based fuel cells are attractive because they will solve many of the world's
pollution problems. An unavoidable by-product of burning oil is carbon dioxide, and carbon
dioxide harms the environment. On the other hand, the only byproduct of fuel-cell engines is
water.
Third, fuel-cell engines will soon be economically competitive because people will spend less
money to operate a fuel-cell engine than they will to operate an internal-combustion engine.
This is true for one simple reason: a fuel-cell automobile is nearly twice as efficient in using its
fuel as an automobile powered by an internal-combustion engine is. In other words, the fuel-
cell powered car requires only half the fuel energy that the internal-combustion powered car
does to go the same distance.