[填空题]In the United States, all kinds of taxes are used by the federal government.

[填空题]The United States has successfully used PVA to provide input into resource exploitation decisions.

[单项选择]The United States has many different kinds of climates. On the west coast the temperature changes very little between summer and winter, but the north central states have a very different kind of climate. In those states, people wear light clothing during the summer, and they need heavy wool or fur clothing in the winter.In the eastern part of the United States, summer temperatures are very different from winter temperatures. Summers are usually hot, winters are usually cold. Spring temperatures are comfortably warm, and autumn temperatures are pleasantly cool.Years ago, people in the cold parts of the United States didn’t often get fresh vegetables and fruits during the winter. Today, however, trucks and trains deliver fruit and vegetables very efficiently to all parts of the United States. In this way, Americans "send their climates" to people in other states.（）
A. The climate varies a little all over the United States.
B. The climate varies a lot in the United States.
C. There is no variation in climate in the United States.
D. The climate is very pleasant all the year round.

[填空题]Innovation ability in the United States used to be the top in the world.

[填空题]In the United States, the authorities require all financial transactions of over ______ to be reported by way of precaution against money laundering.

[简答题]

Lie detectors are widely used in the United States to find out whether a person is telling the truth or not. 61) Polygraphers, the people who operate them, claim that they can establish guilt b v detecting physiological changes that accompany emotional stress. The technique adopted is to ask leading questions such as: "Did you take the money" or "Where did you hide the money", mixed in with neutral questions, and measure the subject’s electrical resistance in the palm or changes in his breathing and heart rate.
Whether lie detectors will ever be adopted on a similar scale in Britain is still a matter of opinion. 62) At first sight, it appears obvious that any simple, reliable method of convicting guilty people is valuable, but recent research not only raises doubts about how lie detectors should be used but also makes it questionable whether they should be employed at all.
63) The point is that, apart from many of the pol