The verses from the Gospel Seryozha knew fairly well, but at the moment when he was saying them he became so absorbed in watching the sharply protruding, bony knobbiness of his father's forehead, that he lost the thread, and he transposed the end of one verse and the beginning of another.
So it was evident to Alexey Alexandrovitch that he did not understand what he was saying, and that irritated him.
He frowned, and began explaining what Seryozha had heard many times before and never could remember, because he understood it too well, just as that "suddenly" is an adverb of manner of action.
Seryozha looked with scared eyes at his father, and could think of nothing but whether his father would make him repeat what he had said, as he sometimes did.