1.Is this sentence correct?<br/><br/>I could have passed the interview, if I knew english.<br/><br/>Would it be correct if I write "had known" instead of "knew".<br/><br/>2.what would be more appropriate?<br/><br/>If it (was/had been) sung by rajnikant instead of dhanush ,it could have become the national anthem.<br/><br/>Thanks