绿爸爸有两个儿子,大儿子叫绿荫(lǜyīn),小儿子叫绿茵(lǜyīn)。可是现在只有绿爸爸一人在家,他的两个儿子去哪儿了呢?那要从一封信说起了……大约是在四个月前,绿爸爸收到了一封来自伦敦奥组委的邀请信,信的内容如下:大名鼎鼎的绿先生:您好!感谢您的家族为我们这个世界创造了美好的生活环境,带来 Green father has two sons, the eldest son called the shade (lǜyīn), the youngest son called lily (lǜyīn). But now only the Green Dad is at home, where are his two sons? It is about to start with a letter ... About four months ago, Green Dad got an invitation from London Olympic Organizing Committee Letter, the letter reads as follows: The famous Mr. Green: Hello! Thank you for your family for this world has created a beautiful living environment, bring