The 不A不B and 不A不B，一A就C structures
Both structures are used in spoken language.
The 不A不B structure
The 不A不B 
structure expresses that if something isn’t done, then a certain result won’t be achieved.
In this structure, "A" and "B" are replaced either with verbs or less often verbs with an object.
structure expresses that if something isn’t done, then a certain result won’t be achieved.
In this structure, "A" and "B" are replaced either with verbs or less often verbs with an object.Scheme
不
verb 1
action
不
verb 2
result
Examples
你怎么不问呢，不问不知道
Why don’t you ask questions? If you don’t ask questions, you won’t know the answers
nǐ zěnme bú wèn ne, bú wèn bù zhīdào
你要记住，考试不准备不及格
Remember that if you don’t prepare for the exam, you won’t pass it
nǐ yào jìzhù, kǎoshì bù zhǔnbèi bù jígé
他今天一直在做饭，不做完不休息
He has been cooking all day today, and he won’t be able to rest until he finishes
tā jīntiān yìzhí zài zuòfàn, bú zuòwán bù xiūxi
Pay attention
Remember the set expressions:
不见不散
不破不立
不打不成相识
不破不立
不打不成相识 The 不A不B，一A就C structure
The 不A不B，一A就C structure is similar to the previous one. But in this structure, “B” usually is 知道 .
The meaning is: “if you don’t do something, you won’t know something; but if you do it, you will get this result”.
structure is similar to the previous one. But in this structure, “B” usually is 知道 .
The meaning is: “if you don’t do something, you won’t know something; but if you do it, you will get this result”.Scheme
不
verb 1
action
不
verb 2
一
verb 1
(就)
verb 3
result
Pay attention
就 can be omitted.
Examples
不看不知道，一看吓一跳
If you don’t see it, you won’t know what it is. But if you do see it, you will be scared
bú kàn bù zhīdào, yí kàn xià yí tiào
这个项目看起来简单，不做不知道，一做就明白多么复杂
This project may look easy, but you’ll realize how difficult it is after you start it
zhè ge xiàngmù kànqǐlái jiǎndān, bú zuò bù zhīdào, yí zuò jiù míngbái duōme fùzá
不哭不放松，一哭就会放松下来
If you don’t cry, you won’t be able to calm down. But if you do cry, you will start to feel better
bù kū bú fàngsōng, yì kū jiù huì fàngsōng xiàlái