试题库在线考试题库-历年真题模拟试题及答案-考博英语在线试题测试中心-希赛网

题库

首页 > 题库 > 中国科学技术大学

Claims left behind in bankruptcy generally have only a _______ chance of being paid, since they are unsecured and not backed by assets.

This time he could afford to make no mistake: his teacher was there _______, watching every move.

Creatively exciting and commercially attractive…You’ve got a movie here that will _______ kids and adults alike.

Despite the recession in Brazil, many job hunters are taking their last savings and investing in English lessons because so many _______ employers want workers with a knowledge of English.

As they attempted to board the vessel, Israeli security guards on board opened fire with pistols, forcing the pirates to _______.

An anonymous letter _______ police to the possibility of a terrorist attack at the airport.

If a person is in a state between sleeping and being awake, often as a result of heat or drinking alcohol, he feels _______.

There exist some proposals, like creating a series of lasers that would sweep the trash back into our atmosphere, where it would mostly burn up.

English is the dominant language in Hawaii, but it is infused with Hawaiian words, phrases and pidgin slang.

The rule will no longer permit us to use as evidence statements that have been obtained using cruel, inhuman, or degrading interrogation methods.

Had spring ever been gentle, so endearing before? Had every little scene, every shop window, every face he passed ever been so wonderfully interesting?

In her long, but ultimately triumphant career, she has been forced to smuggle birth control supplies under her clothing.

Over the centuries both the Nile and the desert sands imperceptibly shifted, and this temple was lost to the world until 1813, when it was accidentally rediscovered by the Swiss explorer Jean-Louis Burckhardt.

Long-term water availability is largely determined by the average conditions in a river basin, but it is often extreme events that cause acute water insecurity.

The tools of the information age can reinforce, rather than erode, the local character of knowledge system.

He told Arab lawmakers who took part in the protest that “the day will come when we will banish you from the national home”.

Many products, including prescription drugs, are regulated by the federal government. However, the states have laws that allow injured consumers to sue a manufacturer.

Protein synthesis begins when the gene encoding a protein is activated. The gene’s sequence of nucleotides is transcribed into a molecule of messenger RNA (mRNA), which reproduces the information contained in that sequence. Transported outside the nucleus to the cytoplasm, the mRNA is translated into the protein it encodes by an organelle known as a ribosome, which strings together amino acids in the order specified by the sequence of elements in the mRNA molecule. Since the amount of mRNA in a cell determines the amount of the corresponding protein, factors affecting the abundance of mRNA’s play a major part in the normal functioning of a cell by appropriately regulating protein synthesis. For example, an excess of certain proteins can cause cells to proliferate abnormally and become cancerous; a lack of the protein insulin results in diabetes.Biologists once assumed that the variable rates at which cells synthesize different mRNA’s determines the quantities of mRNA’s and their corresponding proteins in a cell. However, recent investigations have shown that the concentrations of most mRNA’s correlate best, not with their synthesis rate, but rather with the equally variable rates at which cells degrade the different mRNA’s in their cytoplasm. If a cell degrades both a rapidly and a slowly synthesized mRNA slowly, both mRNA’s will accumulate to high levels.An important example of this phenomenon is the development of red blood cells from their unspecialized parent cells in bone marrow. For red blood cells to accumulate sufficient concentrations of hemoglobin (which transports oxygen) to carry out their main function, the cells’ parent cells must simultaneously produce more of the constituent proteins of hemoglobin and less of most other proteins. To do this, the parent cells halt synthesis of non-hemoglobin mRNA’s in the nucleus and rapidly degrade copies of the non-hemoglobin mRNA’s remaining in the cytoplasm. Halting synthesis of mRNA alone would not affect the quantities of proteins synthesized by the mRNA’s still existing in the cytoplasm. Biologists now believe that most cells can regulate protein production most efficiently by varying both mRNA synthesis and degradation, as developing red cells do, rather than by just varying one or the other.1. The passage is primarily concerned with discussing the ________.2. According to the passage, which of the following can happen when, protein is not appropriately regulated?3. The accumulation of concentrations of hemoglobin in red blood cells is mentioned in the passage as an example of which of the following?4. Which of the following best describes the relationship between the second and third paragraphs of the passage?

Our visual perception depends on the reception of energy reflecting or radiating from that which we wish to perceive. If our eyes could receive and measure infinitely delicate sense data, we could perceive the world with infinite precision. The natural limits of our eyes have, of course, been extended by mechanical instruments; telescopes and microscopes, for example, expand our capabilities greatly. There is, however, an ultimate limit beyond which no instrument can take us. This limit is imposed by our inability to receive sense data smaller than those conveyed by an individual quantum of energy. Since these quanta are believed to be invisible packages of energy and so cannot be further refined, we reach a point beyond which further resolution of the world is not possible. It is like a drawing a child might make by sticking invisible discs of color onto a canvas.We might think that we could avoid this limitation by using quanta with extremely long wavelengths: such quanta would be sufficiently sensitive to convey extremely delicate sense data. And these quanta would be useful, as long as we only wanted to measure energy, but a completely accurate perception of the world will depend also on the exact measurement of the lengths and positions of what we wish to perceive. For this, quanta of extremely long wavelengths are useless. To measure a length accurately to within a millionth of an inch, we must have a measure graduate in millionths of an inch; a yardstick graduated in inches is useless. Quanta with a wavelength of one inch would be, in a sense, measures that are graduated in inches. Quanta of extremely long wavelengths are useless in measuring anything except extremely large dimensions.Despite these difficulties, quanta have important theoretical implications for physics. It used to be supposed that, in the observation of nature, the universe could be divided into two distinct parts a perceiving subject and a perceived object. In physics, subject and object were supposed to be entirely distinct, so that a description of any part of the universe would be independent of the observer. The quantum theory, however, suggests otherwise, for every observation involves the passage of a complete quantum from the object to the subject, and it now appears that this passage constitutes an important coupling between observer and observed. We can no longer make a sharp division between the two in an effort to observe nature objectively. Such an attempt at objectivity would distort the crucial interrelationship of observer and observed as parts of a single whole. But, even for scientists, it is only in the world of atoms that this new development makes any appreciable difference in the explanation of observations.1. The primary purpose of the passage is to .2. According to the passage, quanta with an extremely long wavelength cannot be used to give complete information about the physical world because they .3. The author uses the analogy of the child’s drawing (Para. 1) primarily in order to .4. The author implies that making a sharp division between subject and object in physics is .

Many Americans regard the jury system as a concrete expression of crucial democratic values, including the principles that all citizens who meet minimal qualifications of age and literacy are equally competent to serve on juries; that jurors should be selected randomly from a representative cross section of the community; that no citizen should be denied the right to serve on a jury on account of race, religion, sex, or national origin; that defendants are entitled to trial by their peers; and that verdicts should represent the conscience of the community and not just the letter of the law. The jury is also said to be the best surviving example of direct rather than representative democracy. In a direct democracy, citizens take turns governing themselves, rather than electing representatives to govern for them.But as recently as in 1968, jury selection procedures conflicted with these democratic ideals. In some states, for example, jury duty was limited to persons of supposedly superior intelligence, education and moral character. Although the Supreme Court of the United States had prohibited intentional racial discrimination in jury selection as early as the 1880 case of Strauder v. West Virginia, the practice of selecting so-called elite or blue-ribbon juries provided a convenient way around this and other antidiscrimination laws.The system also failed to regularly include women on juries until the mid-20th century. Although women first served on state juries in Utah in 1898, it was not until the 1940s that a majority of states made women eligible for jury duty. Even then several states automatically exempted women from jury duty unless they personally asked to have their names included on the jury list. This practice was justified by the claim that women were needed at home, and it kept juries unrepresentative of women through the 1960s.In 1968, the Congress of the United States passed the Jury Selection and Service Act, ushering in a new era of democratic reforms for the jury. This law abolished special educational requirements for federal jurors and required them to be selected at random from a cross section of the entire community. In the landmark 1975 decision Taylor v. Louisiana, the Supreme Court extended the requirement that juries be representative of all parts of the community to the state level. The Taylor decision also declared sex discrimination in jury selection to be unconstitutional and ordered states to use the same procedures for selecting male and female jurors.1. From the principles of the U.S. jury system, we learn that .2. The practice of selecting so-called elite jurors prior to 1968 showed .3. After the Jury Selection and Service Act was passed, .4. In discussing the U.S. jury system, the text centers on .

暂未登录

学员用户尊享特权

老师批改作业做题助教答疑学员专用题库高频考点梳理

上一页 1 2 3 4 5 6 下一页