单选题It would be difficult to have a society like ours without public goods such as defense, transportation, and other services. A public good is one that a person can use without reducing the use of it for another person. One of the best examples of a public good is national defense. One person can benefit from our national defense without reducing another person"s benefits. In fact, it is difficult to keep any person in our society from enjoying the benefits of national defense. The market system does not work well in producing public goods. This is because a person who refuses to pay for a public good cannot be kept from using it. Suppose that the neighbors in a high crime area decide to hire a police force. Each neighbor, except Mrs. Smith, agrees to pay $100 a year for it. Mrs. Smith refuses to pay because she knows that if all the others pay the $100, the police will guard the area anyway. So Mrs. Smith can enjoy the services of the police force without paying $100. The market system has no way to deal with this type of problem. For this reason, we cannot ask each person to make a direct payment in the form of product price. Therefore, we collect money for public goods by using taxes.

单选题By the time you get to the office I ______ all the documents for the meeting. A. was preparing B. prepared C. had prepared D. will have prepared

单选题The new facts throw some light ______ the matter.A) atB) inC) onD) of

单选题My son has a headache and a fever. He appears ______ a cold.

单选题Dear Mr. / Ms., We are pleased m introduce Mr. Wang You, our import manager of Textiles Department. Mr. Wang is spending three weeks in your city to develop our business with chief manufacturers and to make purchases of decorative fabrics for the coming season. We shall be most grateful if you will introduce him to reliable manufacturers and give him any help or advice he may need. Your faithfully

单选题The Swedes are among the most charming peoples in Europe. And their charm comes from an apparent contradiction in the national character, They are extremely conservative in social relationships; within the family and when meeting friends and business acquaintances, their conduct is governed by strict social patterns. At the same time, they are one of the most intellectually progressive people in the world. They are always open to new ideas. All social occasions in Sweden are regulated by rules and traditions. And these traditions are expressed in a specific ritual made up of formal bows, handshakes, and greetings. When a visitor enters a Swedish home, he is invariably received with a "Welcome"; when he leaves, his host will tell him "You will be welcome again." These charming phrases are an indestructible part of Swedish social life and they give it an old - world flavor of good manners,

单选题The police investigation discovered that three young men were ______ in the robbery.A) caughtB) involvedC) connectedD) included

单选题They haven't decided ______ the microscope themselves or buy one from the United States. A．if to build B．whether to build C．either to build D．neither to build

单选题Food and clothing arc the bare ______ of life.A) burdensB) necessitiesC) supplementsD) challenges

单选题Hellen is fond of light music, ______ her brother is keen on rock and roll.

单选题Universities across the nation have decided to do more than talk about the rise in the student cheating.

单选题The shops are told how many passengers are passing through the airport at a particular time. and where they are going; staff then know how much people are likely to spend and what they will buy.

单选题Most people do not choose to work ______ the normal retirement age. A. to B. in C. beyond D. under

单选题______, the president is not able to get his own way on every issue.

单选题Jack would rather spend time complaining than ____________ the problem by himself．

单选题Lily looked so sad because she had ______ by her friends.A. laughedB. laughed atC. been laughedD. been laughed at

单选题— I think it is going to be a big problem. — Yes, it could be. I wonder ______ we can do about it. A. if C. what B. how D. that

单选题When a natural history museum wants an exhibit, it often must build it realistically---from a mass of material and evidence brought together by careful research.

单选题We will put off the trip until next Friday, when we won't be so busy,

单选题By 1900 the American automobile age had begun—12 companies produced a ______ of more than 4,000 ears. A. total B. number C. quantity D. whole