直到1990年，在墨西哥尤卡坦半岛的一支石油勘探队偶然发现了一个_爱下问搜题

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问题单项选择题

直到1990年，在墨西哥尤卡坦半岛的一支石油勘探队偶然发现了一个巨大的陨石坑。这个陨石坑的绝大部分淹没在尤卡坦半岛附近的海底，宽度大约为160至240千米。覆盖陨石坑的沉积物的年代表明，这个巨大的陨石坑大约是在6500万年前形成的，正好与恐龙灭绝的年代吻合。这一证据的发现，使科学家们基本达成了共识：恐龙的灭绝正是由于这颗陨石对地球的撞击造成的。这段话表明这样一个观点( )。

A．1990年之前没人会认为恐龙的灭绝是由于陨石对地球撞击造成的

B．陨石坑的发现使科学家对恐龙灭绝的原因的认识更加一致

C．6500万年前的尤卡坦半岛附近地区是恐龙密集的地方

D．陨石的坠毁是自然现象

答案

参考答案：B

解析：[命题提示] 本题主要考查考生理解文意和归纳推断的能力 [解题要点] 正确理解文段意思，把握表明作者观点的句子的含义这段话的中心句是“这一证据的发现，使科学家们基本达成了共识：恐龙的灭绝正是由于这颗陨石对地球的撞击造成的”，表明科学家对恐龙灭绝的原因的认识趋于一致。AC项说法与题意相符，但不是文段主要观点；D项说法文中并未提及。故选B。

完形填空

Anna lived on the side of a valley. One winter, there was a very big flood, and a lot of houses 36  Anna's were washed away. Anna's house was high enough to escape the flood, so when the water had disappeared and the other houses were __37  there with no roof and no walls and all covered with __38 , her house was 39 quite all right.
Her house was quite small, her husband was dead, and she had four children , 40 Anna took in one of the families that had lost 41 in the flood and she 42 her home with them until it was 43 for them to rebuild their houses.
Anna's friends were 44  when they saw Anna do this. They could not understand why Anna wanted to give 45 so much more work and trouble when she already had quite a few children to 46 .
"Well," Anna 47 her friends, "at the end of the First World War, a woman in the town where I 48 lived found herself very poor, because her husband 49  in the war and she had a lot of children, 50  I have now. The day before Christams, this woman said to her children, ‘We won’t be able to have much for 51  this year, so I’m going to 52  only one present for all of us. Now I’ll go and get it.’ She came back 53  a girl who was even poorer than they, and who had no parents. ‘Here’s our present, ’ she said to her children. The children were 54  to get such a present. They welcomed the little girl, and she grew up as their sister. 55  was that Christmas present.

B．just around

B．disappointed

A．explained to

C．talked with

B．might be killed

C．had been killed

D．your birthday

单项选择题

人工牙排列原则中不包括（）

A.恢复解剖生理功能

B.保持义齿稳定

C.根据患者性别不同而区分

D.上下牙列间要有平衡接触关系

E.按照颌弓形态和上下颌弓间的关系排牙