if a then b if a then b truth table if a then b is the form of a statement if a then b fallacy if n a then blank if a happens then b happens how do you write an if then formula if a then b logic if a then b excel formula if a then b symbol if a then b if b then c therefore if a then c if a then b venn diagram and then there were none book back then login then came bronson beatles now and then seek first to understand then be understood by then meaning somebody wanted but so then and then i go and spoil it all by saying if then bash