简述人工修枝的开始年龄，间隔期和修枝高度。
参考答案：
开始修枝的年龄可提早到造林后2-3年；人工修枝间隔期，是指两次修枝中间相隔的年限。大多数针叶树是在第一次修枝后又出现1-2轮死枝后进行第二次修枝。阔叶树早期修枝有利于控侧枝促主干生长，间隔期宜短，一般是2-3年；修枝高度视培育的材种而异。一般修到6.5-7m高度，既满足普通锯材原木的要求。造纸和胶合板材修到4-5m。
| 完形填空 。 In our country every school has a library. I'm 1 you have read many books. You borrow them from the school library and keen them for 2 . Maybe you 3 get books from your parents or friend 4 , If you like reading and want 5 , you may often go to bookshops and buy some yourself. Have you 6 thought of how people make a book? Different people must check it several times 7 it comes out. After __8 _ finishes reading a book, the book passes through the hands of many other people. Everyone in the factory, has to work very carefully because 9 must not be any mistake in it. Many people are busy _10 _ it. They print it on good paper and put the pieces together before it goes to the bookshop. We all like reading. Let's take good care of books. | ||||
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