If i have gone to the party, i would have met Margret 

1.If i have gone to the party , i would have met Margret 

->Had.................................................................................

2.If the news turn out to be true , i will shell my shares at once 

->Unless.....................................................................................

3.Unless he fails  the final examination , he will be able to graduate 

->If.....................................................................................................

4.If the guests arrived this week , there would be no room available 

->Unless..............................................................................................