简述提高森林生产力的途径。
参考答案：
（1）选用适当的培育方式（2）遗传改良（3）林分结构的调控（4）立地的选择和调控。
113号元素原子（质量数是284）的中子数与质子数之差是（ ）
A．58
B．0
C．171
D．60
句型转换。
1. How do you like the weather here? (改为同义句)
______do you 一______the weather here?
2. The boy finished his homework by himself, didn't he? (作否定回答)
______,he ______
3. It was really excitmg,______.(完成反意疑问句)
4. He has gone to the space museum. (改为一般疑问句)
______ he______to the space museum?
5. I'm going to the theme park tomorrow. (对画线部分提问)
______ you going tomorrow?
