生物防治
参考答案：
生物防治是利用有益生物或其他生物来抑制或消灭有害生物的一种防治方法
If a is odd number，the there must exist an integer n such that a2-1=（ ）
A．3n
B．5n
C．8n
D．16n
用arrangement的适当形式完成句子
1. What do you think of marriage?
2. Who is the of the meeting?
3. We have finished all the for the party.
4. Can I an appointment on Monday?
