"但一首好歌人人都喜歡唱,於是就有了很多不同的版本,歌詞在不同的時代也有所改變。"
Just listened to a similar story on NPR:
Woody Guthrie's Indelible Mark On American Culture at http://www.wbur.org/npr/156301144/woody-guthries-indelible-mark-on-american-culture
The Story Of Woody Guthrie's 'This Land Is Your Land' at http://www.wbur.org/npr/1076186/this-land-is-your-land