I think highly of my teacher.
先生を尊敬している
I think I could manage an hour.
1時間なら都合がつきます
I think I'll go for a walk.
散歩に行こうと思う
I think it a pity to waste good food.
おいしい食べ物を残すのは惜しいと思う
I think it quite right people should be respectful to their superiors.
目上の人に礼儀正しくするのはきわめて当然だと思う(◆接続詞thatの省略に注意)
I think it will rain tonight.=It will rain tonight, I think.
(確信はないが)今晩は雨だろう(◆文末だとさらに確信のない言い方)
I think otherwise.
そうは考えない
I think success is when you satisfy yourself.
成功は自分で納得がいく時だと思う
I think that about wraps it up.
これでだいたい区切りがついたと思う
I think things are looking good right now.
今のところ順調だと思う