我认为不是这样。

Wǒ rènwéi bú shì zhèyàng.

I don't think it's like this.

我认为你是对的。

Wǒ rènwéi nǐ shì duì de.

I believe you are correct.

老师认为我进步得很快。

Lǎoshī rènwéi wǒ jìnbù de hěn kuài.

The teacher thinks I am making progress quickly.