Question

In some countries in which there is very little rain at any time, the farmers have to irrigate their fields. Irrigation is easy enough if there is a great river near the crops, and if there is plenty of water in it. Canals carry the river water to the fields when necessary. In some seasons there may be too much water in the river, and the water may flood all the land near it. At other times the river water may not be enough for all the farmers, and then it will be difficult to irrigate the fields.
To prevent these difficulties, a dam may be built across the river. This will store water for dry seasons, and in wet seasons it will prevent the flooding of the land. A great lake will, no doubt, be formed behind the dam, and this may mean that houses and fields will be covered with water. Most people will accept that and will be ready to move to other places. Then the country can have the right amount of water at all times; more crops will be grown, there will be more food for everyone, and there will be no more floods.
Dams have been built for centuries in different parts of the world. Modern dame are usually built of concrete（混凝土）but earth dams were used in India and Sri Lanka about 2500 years ago. There was another across the River Tigris very long ago, and large numbers of irrigation canals were made in Iraq to irrigate the land. The Romans were great dam-builders and there was also a famous dam at Ma’ rubin Arabia.
We cannot use sea water for irrigation; the salt will not allow the crops to grow. Fresh water is always needed, and it is very difficult and costly to make fresh water from sea water. This is done in a few countries, but the fresh water is for drinking. There is not enough at present for irrigation. Perhaps a scientist will one day invent a cheaper way of producing fresh water from the sea.
小題1:The first paragraph mainly talks about         .

A．the problems caused by river water

B．the necessity to irrigate the field

C．the water shortage in some countries

D．the canals carrying water to fields

小題2:A dam is usually built         .

A．to cover the houses and fields

B．for people to have the right amount of water at all times

C．to grow crops better

D．to form a large lake

小題3:The underlined word“that”means        .

A．a(chǎn) dam will be built across the river

B．a(chǎn) dam will store water for dry seasons

C．in wet seasons a dam will prevent the flooding of the land

D．houses and fields will be covered will water

小題4:The third paragraph suggests that        .

A．modern dams are made of concrete

B．Romans once built many great dams

C．there was too much water in 1rap in the past

D．modern dams are better than early dams

Answer 1

ABDB
小題1:A
小題2:B
小題3:D
小題4:B

試題分析：本文講述了大壩蓄水灌溉的知識，并仔細分析了建筑大壩的好處等。
小題1:A 段落大意題。在第一段中主要討論的是河水灌溉的問題，有了大量的河水，人們就可以進行灌溉，要是河水不夠了，那么灌溉就成了問題，故A項正確。
小題2:B 細節(jié)題。根據(jù)第二段前3行To prevent these difficulties, a dam may be built across the river. This will store water for dry seasons, and in wet seasons it will prevent the flooding of the land.說明大壩可以蓄水供人們在任何時候來使用，故B項內(nèi)容正確。
小題3:D 推理題。根據(jù)第二段2,3,4行A great lake will, no doubt, be formed behind the dam, and this may mean that houses and fields will be covered with water. Most people will accept that and will be ready to move to other places.說明這里的that就是指前一句的大壩后面的房子和土地會被大水淹沒，故D項正確。
小題4:B 推理題。根據(jù)本段最后一句The Romans were great dam-builders and there was also a famous dam at Ma’ rubin Arabia.說明羅馬人是建筑大壩的能手，故說明他們曾經(jīng)修筑過多個大壩所以才能這樣說，故B項正確。
點評：本文講述了大壩蓄水灌溉的知識，考查推理題較多，最主要的方法是根據(jù)詞義關(guān)系推斷具體細節(jié)。抓住題干文字信息，采用針對性方法進行閱讀，因為這類題的答案在文章中找到有關(guān)的語群。