From Longman Dictionary of Contemporary EnglishI thinkI thinkPROBABLYused when you are saying that you believe something is true, although you are not sure Mary is in the garden, I think. I don’t think Ray will mind. ‘Do you understand what I mean?’ ‘Yes, I think so.’ ‘Haven’t we met before?’ ‘I don’t think so.’ I thought he was honest, but I was wrong. → think
Examples from the Corpus
I think so• "Is Matt coming to the party?" "I think so."• But you were there. I thought so.• The foundations 243 think so, my friends think so, even I thought so.• Actually, I think so too.• Sound good? I thought so too. 