重点讲解：
1. kill off 被全部杀死；被灭绝；
Their natural predators have been killed off.
它们的天敌被全部杀死@q]I^ZlyY_0Uws。
2. come up with 想出，提出(计划、想法等)；
Howard Wilkinson has come up with an absolute corker of an idea.
霍华德·威尔金森想出了一个绝佳的主意Ff8FQdH2k8(,#DRem;7%。
3. in return 作为回报；作为交换；
These are gestures of genuine friendship with no favours expected in return.
这是友谊的真正表现，不期待任何回报^7hK,qlvTf[)mwFz-G。
4. be made of （由…）构成的；（由…）制成的；
All the furniture was made of wood.
这里所有的家具都是用木料制作的3vS&(p2an8=7+2nD1。