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Where is Mr. White from

A. Because Mr. Li wouldn’t like to meet Mr. White.
Because Mr. Li was not able to get here to meet Mr. White.
C. Because Mr. Li was on business.

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阅读下面短文，回答下面问题。树是一部活档案，树干的年轮就是历史的记录。1901年，美国人道格拉斯发现居住地附近新近砍伐留下的树桩上，都有相同的图案纹理，譬如说，这些树木年轮的外面三圈都较宽，这表明近3年居住地附近环境与气候条件较好，树木生长较快。担相反的结论也可以由此得出。这个发现促使道格拉斯致力于树木年乾的深入研究。他用“同一地区，同时期年轮模式相同”的假设，以“接龙”的方式，来推算老树的初生年份。比如，有一棵被砍伐的百年古树，其砍伐年代不详，但是它的年轮中有一圈与当地一棵1864年砍下的大树的年轮最外圈相吻合。由于最外圈是被砍伐当年的年轮，因此这相吻合的一圈为1864年的年轮。由此向内按每进一圈是一年的方法推算，就可以算出这棵树大约哪一年栽种的。一些科学家还根据年轮推算出发生过酸雨的年份。哥伦比亚大学的雅格比解释说，随着树木越长越老，年轮也变得越来越窄，而酸雨对树木恰恰起着相反的作用。年轮还可以记录下火山爆发与地震。火山爆发时，大量灰尘与气体进入同温层，遮住了阳光，这会使温度降到冰点以下，给树木留下一道叫做“霜轮”的特殊标记。东印度群岛坦波拉山爆发曾使1816年成了“没有夏天的一年”，这个标记甚至出现在南非的树木上。地震也可以给树木造成损害，使树在以后的一些年中形成较窄的年轮。由此看来，倘若说树木年轮“泄漏天机”，似乎并不为过。 (佚名《年轮》) 对下面的说法解释不正确的一项是：

A. “相反的结论”：如果树木某一年的年轮比较窄，那就证明该地这一年环境与气候条件不好。
B. “初生年份”：指树的栽种年份。
C. “这相吻合的一圈”：指1864年砍下的大树年轮的最外圈。
D. “这个标记”：指“霜轮”，即冰点以下树木生长时留下的年轮。

Why don’t birds get lost on their long flights from one place to another Scientists have puzzled over this question for many years. Now they’re beginning to fill in the blanks.Not long ago, experiments showed that birds rely on the sun to guide them during daylight hours. But what about birds that fly by night Tests with artificial stars have proved that certain night - flying birds are able to follow the stars in their long- distance flights.A dove (鸽子)had spent its lifetime in a cage and had never flown under a natural sky. Yet it showed an inborn ability to use the stars for guidance. The bird’s cage was placed under an artificial star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the artificial stars caused a change in the direction of his flight. But the stars are apparently their principal means of navigation(航行)only. When the stars are hidden by clouds, they seemingly find their way by such landmarks as mountain ranges, coast lines, and river courses. But when it’s too dark to see these, the doves circle helplessly, unable to find their way. During daylight hours, birds ().

A. wheel back and forth
B. follow the stars in their flights
C. use sun for guidance
D. are quite likely to get lost

The history of the American people is, (76) , the history of the movement of the American people. They moved from the colonies of the East Coast to the open space of the (77) . They moved from the country and the farm to the city. (78) , Americans have been moving from the cities to the suburbs.Pioneer Americans began (79) from the East Coast to the West 250 years ago. They moved west for many reasons. (80) reason was that they could obtain (81) open space and land (82) farming. Americans liked large open spaces, and they liked the freedom and independence to (83) the land in their own way. Some of the land became farms. Important minerals were discovered in some areas, so some of the land became (84) . Other large areas became cattle ranches. There seemed to be enough land for everybody. But it was a diffieuh (85) of endless work and hardship. 82().

A. of
B. for
C. on
D. in

我国社会主义学校师生关系的基本要求是：___；_；_；___。