1.I'm not sure that she is honest.
2. I'm not sure whether she is honest.
3. I'm sure that she is honest.
4. I'm sure whether she is honest.
I want to know if there any differences between 1 and 2.
Also I wonder if 4 makes sense - and grammatical.
Last edited by wotcha; 26-Apr-2013 at 11:39.
1 is good. 2 would be accepted by many people (chiefly by people who don't recognize a relation between whether and either - so I would prefer 'I'm not sure whether she is honest or dishonest'). 3 is fine. 4 makes no sense.