人体不能同时进行的两项生理活动是（） A．呼吸和消化 B．_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

人体不能同时进行的两项生理活动是（）

A．呼吸和消化

B．心跳和呼吸

C．呼吸和吞咽

D．消化和吸收

答案

答案：C

题目分析：呼吸道和消化道有共同的通道咽，上面有会厌软骨，进食的时候，会厌软骨盖住喉口，食物进入食道，呼吸时，会厌软骨抬起，空气进入喉。因此，呼吸和吞咽不能同时进行。

完形填空

请认真阅读下面短文,并根据所读内容在文章后的空格内填入最恰当的单词. 每空格1个单词，不得用文章中的单词。
A scientist once said that studying the stars from the earth is something like looking up at the sky from the bottom of a swimming pool. Even on the clearest night the earth’s dense atmosphere will dim stars in the sky as it screens out (遮挡) 30 percent of their light. Air turbulence (湍流) causes stars to winkle. Through a telescope, the stars seem to jump around dizzily.
Because the moon has no atmosphere, astronomers are looking forward to setting up an observatory there. On the moon, there will be no clouds to obscure the view. The sky will appear dark at all times, so astronomers can work twenty-four hours a day. Because there is not air turbulence, the stars will steady through a telescope.
Because the moon is relatively near the earth, moon-based astronomers will see the stars in familiar patterns known on earth. They will not need new star maps of the sky. Stars seen from the moon will appear to move very slowly. Because the earth rotates (自转) on its axis once every twenty-four hours, earth-based astronomers see the stars hurry across the sky each night. The moon rotates on its axis only once a month. To astronomers on the moon, the stars will appear to stand almost still. Moon-based astronomers will have much more time to focus their telescopes and take time ---exposure photographs.
On the earth, man-made radio noises jam the airwaves and interfere with the reception of radio signals from certain stars. A radio telescope located on the far side of the moon will be permanently protected from such interference.
It won’t be easy to put telescopes on the moon. However, astronomers are certain the job can be done. They are convinced that the moon is an ideal place to set up an observatory.
Title : The Reasons for establishing an observatory on the moon

Main Comparison	Context
Different 小题1:	There is very 小题2: atmosphere on the moon.
Different 小题1:	On the earth, air turbulence causes stars to twinkle like 小题3: .
Different 小题4:	On the moon, the sky will seem to be in 小题5: .
Different 小题4:	Because of clouds, there is a 小题6: view from the earth.
Different 小题7:	Earth-based astronomers see stars move very 小题8:
Different 小题7:	Stars are seen on the moon to move at a very low 小题9:
In contrast	The moon is 小题10: to be an ideal place to set up an observatory.

填空题

超声波探伤能成功地在（）进行。