可恶的蚜虫（aphids）开始悄悄啃食棉花姑娘（cotton）的叶子。棉花姑娘生病了，她多么盼望医生来给她治病啊！燕子、啄木鸟、青蛙都来帮她治病，但是都帮不上忙。怎么回事呢？最后谁治好了棉花姑娘的病？Let’s read the story.
　　This is Cotton Girl.
　　She lives beside（在……旁边） a tree.
　　The cotton girl is so white！
　　“You are lovely and beautiful，” says the tree.
　　But the cotton girl cries（哭泣） one day.
　　She is sick.
　　“Don’t worry（担心），” says the tree.
　　“Doctors will come and help you.”
　　Doctor swallow（燕子） comes.
　　“What’s the matter？” asks the swallow.
　　“So many aphids are on my leaves！” says the cotton girl.
　　“Can you help me？”
　　“Sorry， I can’t help you，” says the swallow.
　　“I only catch（捕捉） the pests（害虫）in the sky.”
　　“But where is my doctor？” says the cotton girl sadly（难过地）.
　　Doctor woodpecker（啄木鸟） comes.
　　“Dear woodpecker， I’m ill，” says the cotton girl.
　　“Maybe（也许） you can catch the aphids on my leaves.”
　　“I am sorry， I can’t help you，” says the woodpecker.
　　“I can only catch the pests in the tree holes（树洞）.”
　　“Oh， where is my doctor？” says the cotton girl.
　　Doctor frog comes.
　　“Dear frog， I’m ill. Can you help me？” says the cotton girl.
　　“What’s wrong with you？” asks the frog.
　　“Many aphids are eating（吃） my leaves.” says the cotton girl.
　　“Sorry， I can’t help you，” says the frog.
　　“I can only catch the pests in the fields（田野）.”
　　“Oh， my doctor， where are you？” says the cotton girl.
　　Doctor ladybug（七星瓢蟲）comes.
　　“So many aphids on your leaves！” says the ladybug.
　　“I am your doctor. Let me help you.”
　　Ladybug catches the aphids.
　　The cotton girl becomes fine（健康的）.
　　She is happy again.
　　“I’m fine now. Thank you，” says the cotton girl.
　　“It’s my pleasure. I am your doctor，” says the ladybug.
　　知识链接：“活农药”——七星瓢虫
　　七星瓢虫（ladybug）长得非常可爱，红红的背上有七颗黑色的小圆点。它是著名的害虫天敌，捕食麦蚜、棉蚜、槐蚜、桃蚜、介壳虫、壁虱等害虫，可大大减轻树木、瓜果及各种农作物遭受害虫的损害，被人们称为“活农药”。