Which of the following set of statements represents acceptable propositions in respect of teaching- learning relationships? Choose the correct code to indicate your answer. 
i. When students fail in a test, it is the teacher who fails. 
ii. Every teaching must aim at ensuring learning. 
iii. There can be teaching without learning taking place. 
iv. There can be no learning without teaching. 
v. A teacher teaches but learns also. 
vi. Real learning implies rote learning.