简述木材密度的垂直变异。
参考答案：
一般的规律是从基部到顶部，密度下降。
用所给词的适当形式填空。
1.He often _______(do) his homework every day.
2.She___________(read)English now.
3.They are _______(go) to Hawaii for vacation.
4.Does your father________(speak)English?
5._________(send) me a postcard frrom Hong Kong,please
在保险合同中，投保人对保险标的所享有的保险利益在经济上用货币估计的价值额被称为______。
A．保险价值 B．保险金额C．预期价值 D．实际利益
send) me a postcard frrom Hong Kong,please