| Perhaps the most familiar plant
movement belongs to one species of mimosa called the sensitive plant. Within
seconds, it can lower its leaves and make its tiny leaflets close up like
folding chairs. This movement is thought to be initiated by electrical impulses
remarkably similar to nerve signals in animals. But without the animals’
sophisticated motion machinery, the mimosa has had to be creative in devising a
way to move. For motion, the plant depends on tiny, bulb-shaped organs located at the base of each leaf stalk and leaflet. Called pulvini, these organs hold the plant parts in place. When the mimosa is stimulated--say, by a crawling insect or a sudden change in temperature--an electrical impulse sweeps through the plant. This causes potassium and then water to be shifted from certain cells in the pulvini to others, quickly turning one side of the A. geographical distribution of plant and animal species B. location and purpose of the pulvini C. appearance of the mimosa D. process that causes movement in the mimosa [单项选择]Impostion of a discriminating duty belongs to the tariff rates falling into the category of ______.
A. general rates B. preferential rates C. ad valorem duty rates D. special duty rates [单项选择]Which of the following belongs to traditional investment
A. Corporate bonds and buying stock on margin. B. Preferred stock and selling short. C. Government bonds and common stock. D. Trading in commodities and options. [单项选择]Keeping what belongs to others amounts to stealing.
A. 保留属于别人的东西是偷窃。 B. 偷窃别人的东西归为已有。 C. 把别人的东西据为已有就是偷窃。 D. 保留那些别人偷来的东西就是偷窃。 我来回答: 提交
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