So you might know these already, but the first three, the simplest three, I think, I feel like, and in my opinion, you can use all of those to start a sentence where you express your opinion.
所以,你可能已經知道這些,但前三個,也就是最簡單的三個:我認為、我覺得、在我看來,這些都可以用來作為表達觀點的句子的開頭。