I think watching English films is a great way to learn English.

肯定句

I think watching English films is a great way to learn English

否定句

I （ don it ) think watching English films ( is ) a great way to learn English

（翻译原句 "我觉得看英文电影对学习英文是非常棒的！"）

I don't think watching english films is a great way to learn English

don't is
用think引导的句子否定think

don't...to be

don't,is

don't is