Don’t leave the window open文法?

Longman dictionary:
Leave - [transitive] to let something remain (同義詞=stay) in a particular state, position, or condition
e.g. leave something open/empty/untidy etc
Therefore,
leave the window open = let the window stay open
leave the windows closed = let the windows stay closed (中文翻譯亦然)

別讓窗開著 Don’t leave the window open.
Normally, someone will say this request or order if you forget to close the window again after you open it (for some personal reasons).

那麼別讓窗關著的用法為何?
Don't leave the window closed. (closed 本身就是一個形容詞)

如果窗本來是關著的, 要說別讓窗被打開, 是用be opened嗎?
Just say:
Don't open the window, please. (.. keep it closed, thank you.)

1. 先說妳問題的錯誤:

Don’t leave the window open.
別讓窗開著 (X)
別讓一直窗開著 (O)

2. 那麼別讓窗關著的用法為何?

Don't let the windows stay closed.

3. 如果窗本來是關著的 要說別讓窗被打開 是用be opened嗎?

有2種說法:
(A) 反面說法: Don't let the window open.
(B) 正面說法: Keep the window closed.

簡單，keep the windows closed