[al:新概念英语（第1册）第115课（听力强化·中英）]
[ti:Knock, Knock!－敲敲门！]
[ar:© 2011 露珠英语工作室]
[by:http://weibo.com/DewEnglishStudio]
[00:00.00]Let's try the back door.
[00:01.00]让我们到后门去试试。