Correct a sentence, if needed: I don't sure that he can do it a) l am not sure that he can do it; b) l not sure that he can do it; c) The sentence is correct; d) l'm not sure that he can to do it; Помогите, пожалуйста выбрать правильный ответ a), b), c) или d). Заранее спасибо, Николай.