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　　Conversation C

　　Evelyn and Ben are walking home together.

　　Evelyn:Did you know hippos sometimes kill people?

　　Ben:How? By rolling1 over them while they're sleeping?

　　Evelyn:No, silly! Hippos only kill in self-defense.

　　Ben:Then remind me to never make a hippo angry... What about other animals—do they eat hippos?

　　Evelyn:Not really. Hippos almost don't have any natural enemies.

　　Ben:They have friends, though; I always see birds on their backs.

　　Evelyn:Yes! Hippos are great hosts for other animals.

　　Conversation D

　　Ben:Great hosts? Hippos have parties?

　　Evelyn:No! They're a source2 of food for birds.

　　Ben:Birds eat hippos?!

　　Evelyn:No. They eat insects off of a hippo's skin.

　　Ben:I get it. Say, how do hippos mark3 their territory?4

　　Evelyn:They use their urine to tell other hippos to stay away.

　　Ben:Eww! Sounds like they're not good hosts to other hippos!

　　by Alex Adair

　　词汇小补贴：仅供参考

　　●self-defense自卫

　　●insect昆虫

　　●urine尿