题型：阅读选择 题类：模拟题 难易度：普通
福建省泉州市2019届九年级下学期英语升学模拟考试试卷（含听力音频）
We usually think that plants always stay quiet and never speak. Grass doesn't cry when you cut it; flowers don't shout when they're picked. But this view of the world couldn't be more wrong. Plants talk to each other all the time. Their language is one of chemicals.
Over the years, scientists have found that different types of plants, from trees to tomatoes, send compounds(复合物)into the air to help neighboring plants. But exactly how plants receive and act on many of these signals is still a mystery.
Scientists from Kyoto University in Japan looked at tomato plants that had been bitten by insects. To start out, they grew plants in two plastic bags connected by a tube(管子). One plant had been bitten by insects. The other was not bitten.
They found that when insects bite plant leaves, the plants don't sit quietly. They send a chemical called "hexvic" into the air. Humans can't notice it, but these chemicals carry a smell that neighboring plants can notice. This way, neighboring plants realize the danger and begin to give off more "hexvic" to protect themselves.
The same scientists continued their research by placing insects on the plants that had not been bitten. The plants were able to kill nearly 50 percent of the invaders, much more than their neighbor.
It was surprising that the plants that had not been bitten didn't send the chemical until the received a warning message from their infested(受侵的)neighbor, the scientists said. These findings could be used to help farmers with the control of the insects which do harm to their plants.
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