wǒ yào jiǎn féi le.
I am going to lose weight.
shuí xìn na? nǐ dōu shuō guò hǎo duō huí le.
Xiao Lin: 谁信呐？你都说过好多回了。
Who would believe that? You've said this many times before.
zhè cì shì shuō zhēn de, wǎn fàn wǒ yào shǎo chī diǎnr.
I am serious this time. I will eat less in the evenings.
nǎ cì nǐ bú shì chī chēng le hái yào chī, wǒ shuō nǐ hái quán dāng ěr páng fēng.
Xiao Lin: 哪次你不是吃撑了还要吃？我说你还全当耳旁风。
When was the last time you didn't ask for more even though you were already full? Criticizing you is like water off a duck's back.
People use rhetorical questions in order to stress a certain point. "谁信呐"emphasizes the fact that "nobody would believe (you)." "哪次你不是……" is not only a rhetorical question, it also utilizes a double negative in order to emphasize the fact that somebody always does a certain thing.
"耳旁风", which literally translates as "wind passing by the ear", is equivalent to the English idiom, "like water off a duck's back". The phrase is used to describe comments that seem to have no effect on someone.
按字面意思，“耳旁风”可以直接译为“wind passing by the ear”，和英文中的“like water off a duck's back”相当。该词是指某人听了某些话之后并不放在心上。
"说" appears three times in the dialogue. It is commonly used with many meanings. In "你都说好多回了", "说" means "say, talk or speak". For example "说话" (speak/talk), "说出来" (speak out). "说真的" means "I really mean it." The last "说" means "to scold". For example, "老师说了他几句" (His teacher gave him a dressing-down.). "她被说哭了" (She was scolded so much that she cried.)
在以上对话中，“说”字出现了三次。“说”字有很多意思。在“你都说了好多回了”中，说的意思为“say，talk 或者speak”。例如：说话，说出来。“说真的”的意思是指“I really mean it”。最后一个“说”的意思是“scold（责备）”，例如：老师说了他几句；她被说哭了。
Translated from: english.cri.cn