阅读下面短文，在空格处填入一个适当的词或填入括号中单词的正确形式。

Do you know what a “couch (沙发) potato” is? In The Couch Potato by US writer Jory John, the Couch Potato lives a very relaxed life. He spends all day 1. __________ (sit) on the couch.