可不是 / 没说的: you said it!, no complaints
【高72】【高73】固定短语 / fixed patterns
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
可不是 (“how could it not be?”) is a colloquial “you said it!”: you pick up what the other person has just said, and often add a fact. 甲：小孩子长得真快啊！乙：可不是，已经要上小学了。 The 不 is not a negation: the rhetorical question amounts to agreement. It sounds livelier and more complicit than 对 or 是啊.
没说的 has two uses. First “nothing to criticise, excellent”: 新来的领导我都见过了，真是没说的！ Then “it goes without saying, no problem”, often followed by a reservation: 我愿意做这件事，那是没说的，只是我不知道还能做多长时间。 The phrase is invariable (never 没说的了).
Both belong to lively dialogue, almost interjections; you do not write them in a formal text.
Examples
甲：小孩子长得真快啊！乙：可不是，已经要上小学了。
Jiǎ: Xiǎoháizi zhǎng de zhēn kuài a! Yǐ: Kěbùshi, yǐjīng yào shàng xiǎoxué le.A: Children grow up so fast! B: You said it, he's about to start primary school.
甲：这几天真热啊！乙：可不是，听说明天要三十八度。
Jiǎ: Zhè jǐ tiān zhēn rè a! Yǐ: Kěbùshi, tīngshuō míngtiān yào sānshíbā dù.A: It's so hot these days! B: Isn't it? I hear it will be thirty-eight degrees tomorrow.
她做的鱼，味道真是没说的。
Tā zuò de yú, wèidào zhēn shì méishuōde.The fish she cooks tastes truly faultless.
他对朋友，那是没说的，只要开口，从不推辞。
Tā duì péngyou, nà shì méishuōde, zhǐyào kāikǒu, cóng bù tuīcí.As a friend he is beyond reproach: whenever you ask, he never says no.
您愿意帮忙，那是没说的，只是这件事不太好办。
Nín yuànyì bāngmáng, nà shì méishuōde, zhǐshì zhè jiàn shì bú tài hǎobàn.That you are willing to help goes without saying; it is just that this matter is not easy to handle.
新来的领导我都见过了，真是没说的！
Xīn lái de lǐngdǎo wǒ dōu jiàn guo le, zhēn shì méishuōde!I've met all the new leaders, and honestly they are first-rate!
Common mistakes
✗ taking 可不是 as “no, not at all” → ✓ 可不是 = yes, exactly (the 不 negates nothing).
✗ 没说的了 → ✓ 没说的 (the phrase never changes).
✗ 你去不去？ 可不是。 → ✓ 你去不去？ 去。 (可不是 agrees with a remark, it does not answer an open question).