New Words：

poisonous [ˈpɔɪzənəs] adj.引起中毒的；有毒的；分泌毒素的；能毒伤人的
insect [ˈɪnsekt] n. 昆虫；虫子

Sample Sentences：

This gas is highly poisonous.
A lot of poisonous waste water comes from that chemical factory.

Birds and insects are natural enemies.
There is an insect crawling up your back.

natural [ˈnætʃrəl] adj.自然的；天然的；天生的；本能的

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