【名词&注释】
正确答案:A。A.正确 B.错误 更多高中的考试资料下载及答案解析请访问不凡考网学历类考试考试频道。
[单选题]鼠李目的雄蕊对瓣这一特征可能是由具二轮雄蕊的祖先经过外轮雄蕊(对萼)退化而来。( )
A. 正确
B. 错误
查看答案&解析
点击获取本科目所有试题
举一反三：
[单选题]（B）The surprising experiment I am about to describe proves that air is all around you and that it proves down upon you. Air pressure is a wonderful force. When you swim underwater, you can feel water push down your body. The air all around you does the same. However, your body is so used to it that you do not notice this. The pressure is caused by a layer of air called the atmosphere. This layer surrounds the Earth, extending to about five kilometers above the Earth’s surface.
A. The following experiment is an easy one that you can do at home. But make sure that you are supervised, because you will need to use matches. Now foe the experiment！
B. What you need
C. ?A hard-boiled egg without the shell
D. ?A bottle with a neck slightly smaller than the egg
E. ?A piece of paper
F. ?A match
G. Metheod
H. 1） Check that the paper will sit firmly on the neck of the bottle.
I. 2） Tear the paper into strips and put the strips into the bottle.
J. 3） Light the paper by dropping a burning match into the bottle.
K. 4） Quickly sit the egg on the neck of the bottle.
L. Result
M. Astonishingly, the egg will be sucked into the bottle. Your friends will be amazed when you show them the experiment. But be careful when you handle matches.
N. Why it happened
O. As the paper burns, it needs oxygen and uses up the oxygen （air） in the bottle. The egg acts as a seal in the neck of the bottle, so no more air can get inside. This reduces the air pressure inside the bottle. The air pressure must equalize, so more air from outside must enter the bottle. The outside air pressure against the egg and then the egg is pushed into the bottle! The proves that air is all around and that it is pressing down on it.
P. 60. Why is there the need to take care when you are doing the experiment?
Q. The bottle could break.
R. You need to light the paper with a match.
S. The egg needs to be shelled.
T. The egg has to be perfectly placed on the neck of the bottle.
[单选题]We can infer from the last paragraph that the e-nose_____.
A. is unable to tell the smell of flowers
B. is not yet used in greenhouses
C. is designed by scientists at Purdue
D. is helpful in killing harmful insects
[单选题]木犀科(Oleaceae)的模式属是木犀属(Osmanthus)。( )
A. 正确
B. 错误
本文链接：https://www.zhukaozhuanjia.com/download/96gj9x.html
