If-then - should they always be a pair in every sentence?I have a doubt about the usage of if-then. Whenever we write a sentence beginning with 'If', should we also have to put 'then' in it at the appropriate point? That is, is it a mandatory requirement of English to place the pair always. Or is it that there are exceptions where this requirement does not come up and I can put 'if' but not 'then'?
Are any of you aware of this usage and can give guidance on it? Please provide examples for a better understanding.