问题 单项选择题

某些大型低速二冲程十字头柴油机使用短连杆的主要目的是()。

A.降低柴油机高度

B.节省材料

C.增加连杆强度

D.减少侧推力

答案

参考答案:A

解析:大型低速二冲程机采用短连杆的主要目的是降低柴油机的高度,同时增大连杆的摆动角以改善十字头轴承润滑。

阅读理解

The weather predictions for Asia in 2050 read like a story from a doomsday movie.

Many experts and green groups fear they will come true unless there is a united global effort to hold back greenhouse gas outpouring. In the decades to come, Asia---home to more than half the world’s 63 billion people-will change from one climate extreme to another, with tired farmers battling droughts, floods, disease, food shortages and rising sea levels.

“It’s not a pretty picture,” said Steve Sawyer, climate policy adviser with Greenpeace in Amsterdam. Global warming and changes of weather patterns are already occurring and there is more than enough carbon dioxide and other greenhouse gases in the atmosphere to drive climate change for decades to come.

Already, changes are being felt in Asia but worse is likely to come, Sawyer and top climate bodies say, and could lead to mass migration and widespread human disasters. According to predictions, icebergs will melt faster, some Pacific and Indian Ocean islands will have to evacuate(疏散) or build sea defenses, storms will become more intense and insect and water-borne diseases will move into new areas as the world warms.

All this comes with rising populations and demand for food, water and other resources. Experts say environmental worsening such as deforestation and pollution will probably enlarge the results of climate change.

In what could be a sign of the future, Japan was hit by a record of 10 typhoons and tropical storms this year, while two-thirds of Bangladesh, parts of Nepal and large areas of northeastern India were flooded, affecting 50 million people, destroying livelihoods and making tens of thousands ill.

The year before, a winter cold struck and a summer heat wave killed more than 2,000 people in India.

小题1:This passage is mainly about       .

A.what kind of weather we like best

B.the weather predictions for Asia in the future and the reasons

C.how to improve our environment

D.that the world will not be suitable for us to live in小题2:In the future the Asian farmers will have to face the following except       .

A.food shortages

B.droughts

C.wars

D.floods小题3:The underlined word “doomsday” may give us the feeling of        .

A.happiness

B.sadness

C.peace

D.excitement

单项选择题