Quote Originally Posted by RedFox View Post
I'm not sure what is grammatical difference between не... ли and plain ли
This is from my textbook.

не... ли in the subordinate sentence is used as follow:

1. Used with a verb of the main sentence that shows hope for realizing of an action (response); that shows expectation: such as ждать, надеяться, следить, слушать, смотреть
2. Used with a main sentence that shows concern like (Боюсь, .....).