木材通常非常坚硬,与木材中的导管、纤维等细胞壁木质化有关。
参考答案:对
给我们介绍一下你自己。
1. What's your name?
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2. What's your favourite food?
3. What colour are your eyes?
4. What do you do with your ears?
5. How many ears do you have?
商业模式所要解决的核心问题是什么?