“春天时，过敏原往往是树，夏天就是草地，秋天就变成杂草了，”他还补充道，整个冬天都待在家里的人也会因为灰尘或者宠物毛屑而感染过敏。

"In the spring, it's trees; the summer, grasses; and fall, weeds." Being stuck indoors all winter also may cause trouble for those allergic to dust and pet dander, he adds.

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她补充说：“我们可以由鸭嘴兽来跟踪那些改变：我们是如何由爬行类进化到体表被毛，胎生，哺乳喂养后代等等。”

She added, "So we can use them to trace the changes that have occurred as we went from being a reptile, to having fur to making milk to having live-born young."

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她补充说：“我们可以由鸭嘴兽来跟踪那些改变：我们是如何由爬行类进化到体表被毛，胎生，哺乳喂养后代等等。”

She added, "So we can use them to trace the changes that have occurred as we went from being a reptile, to having fur to making milk to having live-born young."

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