问题 单项选择题

在X线摄影中,光电效应的优势是

A.产生有效的散射

B.对胶片产生灰雾

C.增加X线对比度

D.减少曝光时间

E.增加辐射剂量

答案

参考答案:C

解析:光电效应不产生散射线,大大减少照片灰雾,增高X线对比度。

单项选择题
翻译题

完成句子

阅读下列各小题,根据每句后的汉语提示,用句末括号内的英语单词完成句子.

1. ________________her family, Ann had an unforgettable birthday.(accompany)

在家人的陪伴下,安度过了一个难忘的生日.

2. Altogether, Dolly lived six and a half year, only ____________________of the original sheep.(length)

多利总共活了六岁半,只是它的原型羊寿命的一半.

3. The popularity of the film proved how the idea of cloning ____________________.(strike)

这部电影的流行证明了克隆这种思想是怎样使恐惧深入人们内心的.

4. The bird dodo will make an ideal pet ________________. (adore)

渡渡鸟将会成为孩子喜欢的理想宠物.

5. The species became extinct fairly recently, so________________.(condition)

这个物种是近年灭绝的,因此它的DNA仍处于良好的状态.

6. If there is not enough diversity in the group to overcome illness, all their efforts ____________________.(vain)

如果这个群体没有足够的多样性以战胜疾病,那么他们所有的努力都将白费.

7. They built a new hospital ____________________.(with)

他们建了一所新医院,面积是旧的那所的两倍.

8. Not only ____________________________, but also it made the public feel unsafe. (undertake)

这个任务不仅难以执行,而且还会使公众感到不安.

9. The company this year has ________________ as it did last year.(produce)

这个公司今年生产的商品是去年的三倍.

10. A large quantity of birds ____________________from nutritious eggs and the baby birds were

      bound to be taken good care of. (hatch)

许多鸟儿是从营养蛋中孵出来的,这种幼鸟一定要细心照料.