问题 单项选择题

在一次对全市中学假期加课情况的检查后,甲、乙、丙三人有如下结论: 甲:有学校存在加课问题。 乙:有学校不存在加课问题。 丙:一中和二中没有暑期加课情况。 如果上述三个结论只有一个正确,则以下哪项一定为真( )

A.一中和二中都存在暑期加课情况

B.一中和二中都不存在暑期加课情况

C.一中存在加课情况,但二中不存在

D.一中不存在加课情况,但二中存在

答案

参考答案:A

解析: 甲和乙的话为下反对关系(即可以同真,但不能同假),则必有一真,又由题干中只有一个正确,则丙的话必然为假,则一中和二中至少有一个有暑假加课情况,则可推出甲的话为真而乙的话为假,接着可推出所有的学校都存在加课问题。因此一中和二中都存在加课问题,故答案选A。

阅读理解

The dams① aimed at saving Venice from the waves have been backed greatly. After eight years of argument, it plans to build 79 gates across three channels connecting the lagoon around Venice with the Adriatic Sea. The gates would be open most of the time but would be closed if there is a danger to the city.

The project, though, has run into fears that it could worsen Venice’s problems. The city throws waste into the lagoon, and environmentalists fear the dams will cause this pollution to become worse if there is no tide to wash it out regularly. But if there is a tide, the flow can wash away about 550 million cubic meters of the lagoon in a single day, which means that by leaving the dam open for only a few hours, the waste should be cleaned out.

Another piece of good news is that British scientists are confident that the dams will be able to face an expected rise in sea levels caused by global warming. The gates are designed to stand a 22-centimetre rise in sea levels, but many scientists expect a global rise in sea levels of 31cm by 2100.

However, Trevor Davies and Isabel Trigo from University of East Anglia believe the dams are unlikely to broken. Climate change will weaken the local storms in the Adriatic that are the main cause of flood risk. Floodwaters are also a seasonal danger in Venice, usually because of a combination of spring tides and strong winds.

Venice, which rests on wooden piles driven into boggy③ ground, has been sinking for centuries, worsening the encroachment by the sea.

Notes:

① dam  n. 大坝

② lagoon  n. 泻湖

③ boggy  adj. 泥泞的

④ encroachment  n. 蚕食

Choose the best answers according to the above:

1. Which of the following is the main idea of the text?

A. Venice will not disappear into the sea.

B. Dams are designed to protect Venice.

C. Venice are facing dangers from the tides.

D. Global warming makes Venice worse and worse.

2. If the project comes into use, the waste in the lagoon ______.

A. will be washed away by the tides               B. will be sent to the higher places

C. will be carried away by workers                D. will have to be reused by humans

3. According to the idea of Trevor Davies, the dams won’t be broken because ______.

A. the dams are higher than the buildings in Venice

B. there will be no tides or floods in the future

C. the climate all over the world will soon be cold

D. the storms in the Adriatic will be weaker in the future

4. According to the text, we can infer that Venice ______.

A. has been sinking for hundreds of years

B. may suffer from spring tides and strong winds

C. will be under the sea sooner or later

D. will be a city with dams around except 78 gates

单项选择题 A1/A2型题