The nuclear age in which the human race is living, and may soon be dying, began for the general public with the dropping of an atom bomb on Hiroshima on 6 August 1945. But for nuclear scientists and for certain American authorities, it had been known for some time that such a weapon was possible. Work towards making it had been begun by the United States, Canada and Britain very soon after the beginning of the Second World War. The existence of possibly explosive forces in the nuclei of atoms had been known ever since the structure of atoms was discovered by Rutherford. An atom consists of a tiny core called the "nucleus" with attendant electrons circling round it. The hydrogen atom, which is the simplest and lightest, has only one electron. Heavier atoms have more and more as they go up the scale. The first discovery that had to do with what goes on in nuclei was radioactivity, which is caused by particles being shot out of the nucleus. It was known that a great deal of energy is locked up in the nucleus, but, until just before the outbreak of the Second World War, there was no way of releasing this energy in any large quantity. A revolutionary discovery was that, in certain circumstances, mass can be transformed into energy in accordance with Einstein's formula which states that the energy generated is equal to the mass lost multiplied by the square of the velocity of light. The A-bomb, however, used a different process, depending upon radioactivity. In this process, called "fission", a heavier atom splits into two lighter atoms. In general, in radioactive substances this fission proceeds at a constant rate which is slow where substances occurring in nature are concerned. But there is one form of uranium called "U235" which, when it is pure, sets up a chain reaction which spreads like fire, though with enormously greater rapidity. It is this substance which was used in making the atom bomb. The political background of the atomic scientists' work was the determination to defeat the Nazis. It was held—I think rightly—that a Nazi victory would be an appalling disaster. It was also held, in Western countries, that German scientists must be well advanced towards making an A-bomb, and that if they succeeded before the West did they would probably win the war. When the war was over, it was discovered, to the complete astonishment of both American and British scientists, that the Germans were nowhere near success, and as everybody knows, the Germans were defeated before any nuclear weapons had been made. But I do not think that nuclear scientists of the West can be blamed for thinking the work urgent and necessary. Even Einstein favored it. When, however, the German war was finished, the great majority of those scientists who had collaborated towards making the A-bomb considered that it should not be used against the Japanese, who were already on the verge of defeat and, in any case, did not constitute such a menace to the world as Hitler. Many of them made urgent representations to the American Government advocating that, instead of using the bomb as a weapon of war, they should after a public announcement, explode it in a desert, and that future control of nuclear energy should be placed in the hands of an international authority. Seven of the most eminent of nuclear scientists drew up what is known as "The Franck Report" which they presented to the Secretary of War in June 1945. This is a very admirable and far-seeing document, and if it had won the assent of the politicians, none of our subsequent terrors would have arisen. We may infer that the writer's attitude towards the A-bomb is that ______.

The matter is ______ settled; we may look upon it as being settled.

Though steam engines have now passed the ______ of their usefulness, their heritage remains.

These figures are not consistent ______ the results obtained in previous experiments.

The problem has been______my mind all day.

All along the benches men put down their cups and spoons to turn and ______ at the grisly spectacle.

He swallows his words so much that 1 can never______what he is saying.

On Christmas Eve in America the shopping malls are saturated with shoppers in a frantic competition for last minute gifts.

Juan is ______ examining his own feelings and motives: he cannot tolerate introspection.

Mr. Brown's condition looks very serious and it is doubtful if he will______.

The ordinary family colonial North America was primarily concerned with sheer physical survival and beyond that, its own economic prosperity. Thus children were【C1】______in terms of their productivity, and they【C2】______the role of producer quite early.【C3】______they fulfilled this role, their position in the structure of the family was one of【C4】______, and their psychological needs and capacities received【C5】______consideration. 【C6】______the society become more complex, the【C7】______of children in the family and in the society become more important. In the complex, technological society that the United States has become, each member must fulfill a number of【C8】______and occupational roles and be in【C9】______contact with a great many other members. Consequently, viewing children as【C10】______acceptable and necessarily multifaceted members of society means that they are【C11】______more as people in their own right than as utilitarian organisms. This acceptance of children as【C12】______participants in the contemporary family is【C13】______in the variety of statutes protecting the rights of children and in the social and public welfare programs【C14】______exclusively to their well-being. This new view of children and the increasing contact between the members of society has also【C15】______in a surge of interest in child-rearing techniques. People today spend a considerable portion of their time conferring【C16】______the proper way to bring up children. It is now possible to【C17】______the details of the socialization of another person's child by spreading the gospel of current and fashionable theories and methods of child rearing. The socialization of the contemporary child in the United States is a two-way transaction between parent and child【C18】______a one-way, parent-to-child training programs. As a consequence, socializing children and living with them over a long【C19】______of time is for parents a mixture of【C20】______, satisfaction, and problems."

Not a few excellent proposals by the countries of the third world have been ______ to the United Nations, acceptance of which will strengthen peace and lessen the danger of war.

We made plans for a visit, but______difficulties with car prevented it.

My friend had no ______ of helping the man who was acting too rudely.

On the morning of September 11th

Many old houses have been ______ in order that new big buildings may be built.

In the last decade

Hydrogeology is the study of water and its properties, including its______and movement in and through land areas.

She's cute, no question. Symmetrical features

Taking photographs is strictly ______ here