正确答案: A

正确

题目：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。( )

解析：A

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举一反三的答案和解析：

[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.

You need to light the paper with a match.

[单选题]We can infer from the last paragraph that the e-nose_____.

is not yet used in greenhouses

[单选题]木犀科(Oleaceae)的模式属是木犀属(Osmanthus)。( )

错误