we say: 你是很棒的老师，这个视频对我很有帮助。 Nǐ shì hěn bàng de lǎoshī, zhège shìpín duì wǒ hěn yǒu bāngzhù. You are a great teacher and this video helped me a lot. thank you for you watching and feedback！
although both meaning of "only," but it is better do not to interchange them. the most differenc that "只有" (zhǐ yǒu) is usually placed in the first half of a sentence or at the beginning of the sentence: "只有我知道，别人不知道" ("Only I know, others don't know"). on the other hand, "才" (cái)placed in the latter part of a sentence: "妹妹有两个苹果，我才有一个" ("My younger sister has two apples; I only have one"). such two words to use.
