"Can you repeat that, please?" (你能再说一遍吗?)
"Sorry, I didn't catch that. Could you say it again?" (对不起,我没听清楚,你能再说一遍吗?)
"Could you speak a little slower, please?" (你能说得慢一点吗?)
"What do you mean by (insert phrase/word)?" (你说的(某个词或短语)是什么意思?)
"I'm sorry, I don't understand." (对不起,我不明白。)
"Could you explain that in a different way?" (你能换一种方式解释一下吗?)
"Could you give me an example?" (你能举个例子吗?)
"Let me clarify what you just said. Did you mean (insert interpretation)?" (让我澄清一下,你刚才说的是(某个解释)吗?)
"I agree with you (or) I disagree with you because (insert reason)." (我同意你的看法,因为……;我不同意你的看法,因为……)
"In my opinion (or) as far as I'm concerned, (insert opinion)." (在我看来,……;就我而言,……)