多普勒天气雷达可以得到哪三种基本信息？

如图R₁和R₂是材料相同、厚度相同、表面为正方形的导体，正方形的边长之比为2：1．通过这两导体的电流方向如图所示，则这两个导体电阻之比为R₁：R₂=______．你认为这种关系对电路元件改进的意义是______．

有下列事实，其中符合质量守恒定律的是（　　）

①蜡烛燃烧后，质量变小  

②铁制品生锈后，质量增加  

③湿衣服晾干后，质量比潮湿时减小  

④石灰水放在敞口容器内，质量增加．

A．①②④

B．②③④

C．①③

D．①②

In the dining room of my grandfather’ s house stood his heavy clock. Meals in the dining room were a (21) for our four generations to become one. My grandfather’ s clock always stood like a trusted old family friend, (22) us playing jokes and tellingstories, which was already a (23) of our life.

When I was a child, the old clock interested me. I watched and listened to it during (24) I was surprised how at (25) times of the day, the clock would strike three times, six times or more, with a wonderful great (26) that echoed throughout the house. The clock chimed year after year, a part of my (27) , a part of my heart.

Even more (28) to me was my grandfather’s special action each day. He meticulously (29) the clock with a special key each day. The key was magic to me. It (30) our family’ s magnificent clock ticking and striking all year round.

25（）

A.time 

B.possibility 

C.problem 

D.pleasure

A plane crash in Western Russian killed Polish President Lech Kaczynski and the other 96 political and military officials on board on April 10. The accident has led to huge national mourning in Poland. But it may provide an opportunity for reconciliation (和解) between Poland and Russia, countries that have a troubled relationship.

Many from the political elite were lost in the crash. Beside the president, the dead include the army chief of Staff, the head of National Security Bureau, the national bank president, the deputy foreign minister and other members of parliament.

The Polish delegation was heading to Russia to mark the 70 th anniversary of the Katyn Massacre (屠杀) when the accident occurred. In 1940, about 22,000 Polish soldiers, intellectuals, and officials captured after the Soviet Army invaded Poland in 1939, were killed secretly by Soviet police in the forest of Russia’s Katyn.

The Katyn Massacre had been a sensitive topic between the countries. The former Soviet Union always denied responsibility for the massacre. It was not until 1992 that Russian released archived documents about the killing.

Katyn is merely a short chapter in Poland and Russia’s long and troubled history. In the 18 th century, along with Prussia, (then an important part of Germany) and Austria. Russia participated in three carve – ups of Poland. In 1795, after the third carve – up, the country was erased from the map of Europe. It was in 1918 that Poland regained its independence. But in 1939, at the beginning of the World War II, it was invaded by Germany and the Soviet Union under a secret pact. After the war, Poland became a communist country with close ties to the Soviet Union.

In 1989, Poland switched to capitalism and pursued a pro – West position. The most recent tension between the two countries was in 2008. That year, Poland decided to have a US missile shield (导弹防御系统) on its soil, while neighboring Russia threatened to aim missiles at Poland.

But the plane crash has created a chance for reconciliation, with Russia sharing the sadness of Poland. Russia has declared April 12 a day of mourning for the victims. Flags flew at half – mast in Moscow. And earlier on April 7, Russia Prime Minister Vladimir Putin became the first Russian leader to mark the anniversary of the massacre.

“I think it should improve relations between the two countries, as Russians feel our grief,” said Radek Sikorski, Pland’s foreign minister.

66．Put the following events in order of time.

①The Katyn Massacre

②Poland switched to capitalism.

③Russia divided Poland with Austria and Prussia.

④Poland became a communist country.

⑤Poland was invaded by the Soviet Army.

A．③①④⑤② B．③⑤①④②  C．①③⑤④②  D．①⑤②④③

67．After the accident, which of the following did Russia do to share the sadness of Poland?

A．Flags were lowed to half – mast in the capital city of Russia.

B．Russia threatened to aim missiles at Poland.

C．Russia declared the day when the accident happened a day of mourning for the victims.

D．Vladimir Putin marked the anniversary of the massacre.

68．Which of the following is TRUE according to the passage?

A．The Katyn Massacre was the very beginning of Poland and Russia’s trouble relationship.

B．In 1939 about 22,000 Polish soldiers, intellectuals, and officials were killed by Soviet police in the forest of Russia’s Katyn.

C．Altogether 96 political and military officials were killed in the accident.

D．The relationship between Poland and Russia has not always been tense since the three carve – ups of Poland in the 18 th century.

69．It can be conclude from the article that        .

A．the relationship between Poland and Russia will be even tenser than before

B．Poland will cancel its plan to mark the anniversary of the Katyn Massacre

C．no Russian leaders have marked the anniversary of the massacre before, though Russia released the truth in 1992.

D．Poland will forgive Russians, for they showed great sympathy after the accident.

70．What would be the best title for the passage?

A．The troubled relationship between Russia and Poland.

B．Poland and Russia united by tragedy.

C．The 70 th anniversary of the Katyn Massacre.

D．A plane crash killing Polish president.

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