汶川地震后，我国动用飞机对灾区进行航空摄影，其镜头焦距为50mm_爱下问搜题

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问题选择题

汶川地震后，我国动用飞机对灾区进行航空摄影，其镜头焦距为50mm，像到镜头的距离约（　　）

A．略小于50mm

B．略大于50mm

C．100mm

D．50mm或100mm

答案

由于航拍所用的是照相机，所以所照的景物应该在2倍焦距以外，而像必须介于1倍焦距与2倍焦距之间；且此时照相机的焦距为50mm，所以底片上的像到镜头的距离介与50mm和100mm之间；又由于是航拍，所以物距非常大，故此时的像应该略大于焦距．

故选B．

阅读理解

阅读理解。

SINA-In order to let people go out more easily during the 2008 Olympic Games, Beijing
is going to start a special bus line and seven more night bus lines. 40% of the taxis will be in
service for 24 hours. The subway will run longer hours, too. (December 27, 2007)

YAHOO-An old man called Shen Yuanyan made five Fuwa toys with 6,000 pieces of
paper. It took him a few months to finish them. Mr. Shen will make another five bigger Fuwa toys
and send them to Beijing. (January 7, 2008)

BAIDU-The Olympic Flame (圣火) has arrived in Beijing, showing that the Olympic
Games in China will soon begin. From today, the torch (火炬) will carry the Flame across the
world. (March 31, 2008)

XINHUA-Yang Yang, a famous Chinese skater, received the Beijing Olympic torch
from a leader in Sanya, May 4, 2008. Yang ran the first 200 meters during the torch relay (接力) in
Sanya, the first leg in the Chinese mainland (大陆). (May 4, 2008)

1. ______ isn't mentioned in the news above.

A. The bus
B. The taxi
C. The subway
D. The plane

2. The old man's Fuwa toys were made of ______.

A. glass
B. paper
C. cotton
D. silk

3. The torch has carried the Flame across the world since ______.

A. December 27, 2007
B. January 7, 2008
C. March 31, 2008
D. May 4, 2008

4. In the Chinese mainland, the first leg of the torch relay started in ______.

A. Beijing
B. Chongqing
C. Shanghai
D. Sanya

5. There ______ of news about the Olympic torch relay here.

A. is only one piece
B. are two pieces
C. are three pieces
D. are four pieces

填空题

一般说来，动物越高等，形态结构越（），后天性行为也越（），而且后天性行为在动物的全部行为活动中所占的比重（）。