Rubber differs from plastics______it is produced naturally and not in the lab.

She studied hard at school when she was young, ______contributes to her success in her career.

If I had the time, I______on a holiday like that in Spain.

He has made another wonderful discovery, ______of great importance to science.

The century-old______between the two tribes eventually ended through the persistent efforts of the local government.

The government is determined to______an end to inflation.

Horses have more highly developed______of sight and hearing than humans.

If you get into difficulties, don't hesitate to ask ______advice.

Smith would rather have left for San Francisco than______in New York.

In what now seems like the prehistoric times of computer history, the early post-war era (战后时期) , there was a quite widespread concern that computers would take over the world from man one day. Already today, less than forty years later, as computers are relieving us of more and more of the routine tasks in business and in our personal lives, we are facing with a less dramatic but also less foreseen problem. People tend to be over-trusting (过分信任) of computers and are reluctant to challenge their authority. Indeed, they behave as if they were hardly aware that wrong buttons may be pushed, or that a computer may simply malfunction(失灵). Obviously, there would be no point in investing(投入) in a computer if you had to check all its answers, but people should also rely on their own internal computers and check the machine when they have the feeling that something has gone wrong. Questioning and routine double checks must continue to be as much a part of good business as they were in pre-computer days. Maybe each computer should come with the following warning: for all the help this computer may provide, it should not be seen as a substitute for fundamental thinking and reasoning skills.

I went to______London yesterday and saw______strange old man and a little girl, begging by the roadside.

It seems like every day there's some new research about whether our favorite drinks are good for us.(76) One day, science says a glass of red wine a day will help us live longer . The next day, maybe not. It seems journalists are pretty interested in wine research and the same might be said for coffee. Now, there's been a lot of research into whether coffee's good for our health. "The results have really been mixed," admits Neal Freedman who led the coffee study and published his findings in a medical journal recently. "There's been some evidence that coffee might increase the risk of certain diseases and there's also been maybe more recent evidence that coffee may protect against other diseases as well." Freedman and his colleagues undertook the biggest study yet to look at the relationship between coffee and health. They analyzed data collected from more than 400,000 Americans ages 50 to 71 participating in the study. "We found that the coffee drinkers had a modestly lower risk of death than the non-drinkers," he said. Here's what he means by "modestly": those who drank at least two or three cups a day were about 10 percent or 15 percent less likely to die for any reason during the 13 years of the study. When the researchers looked at specific causes of death, coffee drinking appeared to cut the risk of dying from heart disease, lung disease, injuries, accidents and infections. Now, Freedman stressed that the study doesn't prove coffee can make people live longer. A study like this can never prove a cause-and-effect relationship.(77) All it can really do is to point researchers in the right direction for further investigation . And even if it turns out that coffee is really good for you, scientists have no idea why.

I remember______to help us if we ever got into trouble.

There are many older people in the world and there will be many more. A little-known fact is that over 60 percent of the older people live in developing countries. According to the World Health Organization, by 2020 there will be 1 billion, with over 700 million living in developing countries. It is a surprising fact that the population ageing is particularly rapid in developing countries. For example, it took France 115 years for the proportion of older people to double from 7 percent to 14 percent. It is estimated to take China a mere 27 years to achieve this same increase. What are the implications of these increased numbers of older folk? One of the biggest worries for governments is that the longer people live, the more likelihood there is for diseases and for disability. Attention is being paid to the need to keep people as healthy as possible, including during old age, to lessen the financial burden on the state. Another significant problem is the need for the younger generations to understand and value the older people in their society. In some African countries, certainly in Asia, older people are respected and regarded as the ones with special knowledge. Yet traditions are fading away daily, which does not ensure the continued high regard of older people. As society changes, attitudes will change. Much needs to be done to get rid of age discrimination(歧视)in employment. Life-long learning programs need to be provided to enable older people to be active members in a country's development. Social security policies need to be established to provide adequate income protection for older people. Both public and private schemes are vital in order to build a suitable safety net. To achieve equality in such matters will take considerable time and effort. One thing is sure: there is no time to be lost.

______you've found, you must give it back to the owner.

______it is long after dark, he is still wearing black sunglasses.

If you are a member of a club, you must______to the rules of that club.

He was writing______the glass suddenly fell on the floor.

Extreme shyness can get______of language development.

I went to ______Shanghai yesterday. On ______train I met a famous pop star.