[单项选择]One impact that the burning of （　） fuels has had on the Earth’s environment has been the increase of carbon dioxide in the earth’s atmosphere.
A. vehicle
B. oil
C. gas
D. fossil

[单项选择]One impact that the burning of （　） fuels has had on the Earth’s environment has been the increase of carbon dioxide in the earth’s atmosphere.
A. vehicle
B. oil
C. gas
D. fossil

[单项选择]Passage One
For decades, heart disease has had the honor of being the leading killer of Americans. Most heartrelated deaths happen among the elderly. But a new study finds that an alarming portion of heart failure cases are occurring in a much younger group, especially among African Americans.
In the first large-scale study to document the extent of the race gap in heart disease, researchers report that one in 100 black adults develop heart failure in their 30s and 40s-a rate 20 times higher than that of similarly aged white adults. "What these data point out is that it’s important to recognize that disease patterns differ in different populations," says Dr. Kirsten. "We would have completely missed this at-risk group had we only been looking at older age groups."
The new report is a large government-funded survey. The aim of the study was to document the frequency of heart disease among young adults, so researchers recruited more than 5,000 volunteers a
A. heart disease is no longer the leading killer of Americans
B. heart disease can be well controlled at a younger age
C. chances of developing heart disease are equal among the young and the elderly
D. African Americans are more likely to develop heart disease at a younger age

[单项选择]Although he has had no formal education, he is one of the（）businessmen in the company.
A. shrewdest
B. sternest
C. nastiest
D. alertest

[填空题]My father has had one of his (tooth)（）taken out.

[填空题]My father has had one of his (tooth) ______ taken out.

[填空题]

conglomerate has had decided to purchase a European firm. "The best acquisitions in the United States have already been picked, " the president told the board of directors. "However, I’m

[简答题]Relativity theory has had a profound influence on our picture of matter by forcing us to modify our concept of a particle in an essential way. (46) In classical physics, the mass of an object had always been associated with an indestructible material substance, with some "stuff" of which all things were thought to be made. Relativity theory showed that mass has nothing to do with any substance, but is a form energy. Energy, however, is a dynamic quantity associated with activity, or with processes. (47) The fact that the mass of a particle is equivalent to a certain of energy means that the particle can no longer be seen as a static _object, but has to be conceived as a dynamic pattern, a process involving the energy which manifest itself as the particle’s mass.
(48) This new view of particles was initiated by Dirac when he formulated a relativistic equation describing the behavior of electrons. Dirac’s theory was not only extremely