一个圆柱体的体积是90立方分米，如果底面面积是30平方分米，那么它的高是____

Although many Chinese students say that their knowledge of English grammar is good, most would admit that their spoken English is poor. Whenever I speak to a Chinese student, they always say,“My spoken English is poor.” 小题1:I would like to suggest that there may be some reasons for their problems with spoken English.

First, they fail to find suitable words to express themselves due to a limited vocabulary.小题2:However, you can speak with a limited vocabulary, if you choose a positive attitude. Others will follow you as long as you use the words that you know.

  小题3:Sometimes they make mistakes when they are speaking because they are shy and nervous. Yet students should remember that their goal should be FLUENCY NOT ACCURACY. Your aim in writing is to be accurate following the rules for grammar and using the right words and spelling them correctly. However, in speaking your aim is fluency. You want to get your message across, to talk to someone in English, as quickly and as well as you can, even though sometimes you may use a wrong word or tense, but it doesn't matter.  小题4:

The third reason is that not enough attention is paid to listening. You have one mouth but two ears! All that hearing is necessary for you to start speaking.

Fourth, most Chinese students are reactive rather than proactive language learners. Instead of actively seeking out opportunities to improve their spoken English they passively wait for speaking opportunities to come to them and wonder why their English always remains poor. 小题5:  

A．The person you are speaking to will understand you and make allowances for any mistakes he hears.

B．They may try to avoid making similar mistakes next time.

C．Obviously the better answer is to expand their vocabulary.

D．If you have this proactive outlook, then you will see English opportunities wherever you go.E. However, their spoken English does not have to remain“poor”!

F. Second, they are afraid of making mistakes.

G. The second reason lies in the reluctance of using what has just been learned.

如图是鸟卵的结构图，请据图作答．

（一）图中（1）______ 的作用是______．

（二）已经受精的卵，发育成雏鸟的结构是____________．

（三）鸟卵中已受精卵的胚盘比没受精卵的胚盘体积要______且颜色要______．

局部器官长期受压迫，当压力突然解除，该组织器官会发生( )。

A．贫血后充血

B．轴突反射性充血

C．侧枝性充血

D．炎性充血

E．以上都是

NASA’s Mars detector (探测器), Opportunity, succeeded in finding signs that water once existed on the planet. Opportunity landed on Mars in January. Scientists now believe that the planet could once have supported life.

This discovery was chosen by Science, one of the world’s leading magazines, as the most important scientific achievement of 2004 last Friday.

“This little, wheeled, one-armed box went around another planet and has done something no human has ever managed,” according to Science. “It has discovered another place in the universe where life could once have existed.”

“Although we still can’t say that life could have existed in this environment, it is now certain that there was water on Mars,” said Steve Squyres, one of the scientists working on the Mars mission. The evidence comes from pictures and chemical readings taken by Opportunity. It includes marks on rocks like those caused by flowing water on Earth and salty chemicals like those found in dried-out sea-beds. Scientists said the new evidence proved beyond doubt that water has been existed on Mars. But it is still unknown whether the water on Mars was like an ocean or just ice.

While Opportunity has not found any signs of life, the presence of water means life is possible. “In everything we know about life on Earth, there is no example without liquid water,” Squyres said. “So water is important for the search for life on Mars.”

Researchers agree that a future mission (任务) should bring back physical samples (样品). But some scientists worry about the risk that this could introduce dangerous foreign creatures to Earth. “The problem here is how to get the samples back,” Squyres replied. “I think it is our responsibility to limit any risk.”

1. ________ prove that water existed on Mars.

A. The physical samples with salty chemicals      B. The marks on rocks and salty chemicals

C. Scientific achievements of 2004              D. Creatures from Mars

2. Which of the following is true according to the text?

A. It is now certain that there was water on Mars.

B. The water on Mars was like an ocean.

C. Evidence of life on Mars has been found.

D. Search for life on Mars is a great risk to humans.

3. How did scientists draw the conclusion that there was water on Mars?

A. The world’s leading magazine has announced the fact.

B. Scientists have taken many pictures and chemical readings on the Mars.

C. Astronauts have got some rocks from Mars.

D. Scientists have made a study of the pictures and readings sent back by Mars detector.

4. It can be inferred that, if the creatures from Mars came to Earth, ________.

A. they would be kind to humans    B. they would be cruel to humans

C. they would be a great danger to Earth

D. it would be hard to say whether it would be a good news or bad news

金属材料抵抗冲击载荷的作用而不被破坏的能力，是金属材料的（）机械性能。