[填空题]Although we already know a great deal about influenza, it is difficult for epidemiologists (流行病学家), who study infectious disease, to (36) when and where the next flu epidemic will occur, and how (37) it will be. There are three kinds of influenza virus, known as A, B and C. Influenza C virus is relatively stable and causes mild (38) that do not spread far through the population. The A and B types are (39) , and are responsible for the epidemics that cause frequent concern. Following any virus attack, the human body builds up antibodies which confer (给予) immunity to that strain of virus, but a virus with the capacity to change its character is able to bypass this (40) . Variability is less developed in the influenza B virus, which affects only human beings. An influenza B virus may cause a widespread but will have little effect if (41) into the same community soon afterwards, since nearly everyone will have built up

[填空题]Although we already know a great deal about influenza, it is difficult for epidemiologists (流行病学家), who study infectious disease, to (36) when and where the next flu epidemic will occur, and how (37) it will be. There are three kinds of influenza virus, known as A, B and C. Influenza C virus is relatively stable and causes mild (38) that do not spread far through the population. The A and B types are (39) , and are responsible for the epidemics that cause frequent concern. Following any virus attack, the human body builds up antibodies which confer (给予) immunity to that strain of virus, but a virus with the capacity to change its character is able to bypass this (40) . Variability is less developed in the influenza B virus, which affects only human beings. An influenza B virus may cause a widespread but will have little effect if (41) into the same community soon afterwards, since nearly everyone will have built up

[单项选择]

We have recently heard a great deal about the bad effects of computers on our social and economic institutions. In industry, computers mean automation, and automation means unemployment. The United States, with its extravagant investment in computers, is plagued (使得灾祸，烦恼) by unemployment for unskilled workers. Already computers have begun to displace workers whose tasks are simple. The variety of jobs, formerly done only by humans, that the machine can perform more rapidly, accurately, and economically, increases with each new generation of computers, if we follow this trend, say the pessimists (悲观主义者), we are faced with the prospect of mass unemployment for all but a handful of highly trained, highly intelligent professionals, who will then be more influential and overworked than they are now. Only recently a distinguished English physicist predicted that within twenty years electronic engineers might have to become conscientious objectors in order to prevent these machines from
A. that computers are misleading
B. that computers have caused industrial strife
C. that we are able to build bigger and faster computers
D. that we can make the most humane and intelligent use of computers

[多项选择]You know a great deal about economics,______

[单项选择]

The Sea

What do you know about the sea We know that it looks very pretty when the sun is shining on it. We also know that it can be very rough when there is a strong wind. What other things do we know about it
The first thing—to remember is that the sea is very big. When you look at the map of the world you will find there is more water than land. The sea covers three quarters of the world.
The sea is also very deep in some places. It is not deep everywhere. Some parts of the sea are very shallow. But in some places the depth of the sea is very great. There is one spot, near Japan, where the sea is nearly 11 kilometres deep! The highest mountain in the world is about 9 kilometres high. If that mountain were put into the sea at that place, there would be 2 kilometres of water above it! What a deep place!
If you have swum in the sea, you know that it is salty. You can taste the salt. Rivers, which flow into the sea
A. Because the deepest part of the sea is very cold.
B. Because the deepest part of the sea is very rough.
C. Because the pressure of water at great depths is unendurable.
D. Because fierce fish usually live there.