不知就里

不知就裡
bùzhījiùlǐ
  1. unaware of the inner workings
  2. naive
  3. unwitting

CEDICT

to not know the inside story; to be unfamiliar with the details of the situation

Wiktionary

不知详细的情况。《初刻拍桉惊奇．卷二九》：「蜚英起初还推一向在阁下睡，不知就裡，被打不过，只得把来踪去迹细细招了。」《文明小史．第一○回》：「两旁看审的人不知就裡，见了奇怪，三三两两，交头接耳的私议。」也作「不知究理」。

重編國語辭典

Entry Composition

1 不知 bùzhī
  1. not to know
  2. unaware
  3. unknowingly
  4. fig. not to admit (defeat, hardships, tiredness etc)
2 就里 jiùlǐ inside story

Related entries

天真 tiānzhēn
  1. naive
  2. innocent
  3. artless
你太天真了。

You're so naive.

You're too naive.

Source: Tatoeba

不知轻重 bùzhīqīngzhòng
  1. lit. not knowing what's important (idiom); no appreciation of the gravity of things
  2. naive
  3. doesn't know who's who
  4. no sense of priorities
涉世未深 shèshìwèishēn
  1. unpracticed
  2. inexperienced
  3. naive
  4. unsophisticated
憨 hān
  1. silly
  2. simple-minded
  3. foolish
  4. naive
  5. sturdy
  6. tough
  7. heavy (of rope)
素朴 sùpǔ
  1. simple
  2. unadorned
  3. unsophisticated
  4. naive