题目内容
We cannot figure out ________ quite a number of insects, birds, and animals are dying out.
A. that B. as C. why D. When
C
解析:
主要测试宾语从句。分析句子结构可知：动词短语figure out缺少宾语从句，同时后面句子中缺少状语，再结合答案可知能做状语引导宾语从句的词只有C和D，但是when又不符合语境。句子意思：我不能理解为何许多昆虫、鸟儿和动物濒临灭绝。例如：The teacher didn't figure out why the youngest boy in the class was always being late for school。老师不理解为何年龄最小的男孩上学总是迟到。
小学学习好帮手系列答案
小学同步三练核心密卷系列答案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.
【小题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 |
| 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 |
| A．a dam will be built across the river |
| B．a 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 |
| 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 |