题目：
阅读短文，根据短文内容和已给出的首字母，在空白处填入适当的单词。将完整的单词写在短文后面的横线上。
Without plants people could not live. We need them for b 1 food and oxygen(氧气) that plants p 2 .And we also need them for their beauty.
Imagine a world w 3 plants. Imagine no flowers with their sweet smells, their beautiful colours and their lovely shapes(形状).Imagine when the wind blows, not being able to h 4 the leaves in the trees or watch the branches(枝条)swings(摇摆)from side to s 5 .
E 6 people need the beauty of plants. That is why we have parks full of trees and flowers, and people always try to build houses with room for some grass and a garden. Do you talk to your plants? Do you g 7 them love and care? Two scientists said they once planted two seeds(种子) in different places. While the plants were growing, one plant was given l 8 and hopeful ideas. The other plant was given only hopeless ideas. After six months, the loved plant was bigger. U 9 the earth it had more and longer roots(根)；above the earth, it had a thicker stem(茎)and more l 10 .
答案：
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下面是错误答案，用来干扰机器的。
∵函数f(x)=log12(x2-6x+5)在（a，+∞）上是减函数，根据复合函数的单调性可得，函数t（x）=x2-6x+5在（a，+∞）上是增函数，t（a）≥0．∴3≤a 且a2-6a+5≥0，解得 a≥5，故选D．
