Struggling with the definite article 1.1 'The father of one of my students' - we take THE because here we have a qualifying clause with OF. It wouldn't make any sense to ask 'Which father of one of your students' because taking THE pre-empts the question. 1.2 'That guy married the daughter of his bank manager' the same applies to this case. The important point is that his bank manager was the father of the woman he married so it doesn't matter how many daughters the manager actually has. 1.3 The first person to run the mile in under four minutes was Roger Bannister. It is said in the predicate who the person is so asking 'Which first person to run the mile in under four minutes?' would be incoherent. 1.4 It's a film about the life OF A POPULAR EXPLORER. Again. It is stated using the qualifying clause with OF. But here I found a sentence with OF with an indefinite article. 1.5 Cars are a major source of pollution in cities. There are lots of different sources in this World but this source is singled out and defined so it should have been 'the major source of pollution' instead. What's wrong with my version? 1.6 'I want to show you a photo of Jane and me.' A photo is defined by the second part so we know what photo the speaker decided to show. I might be wrong and the last two examples don't strict the number of possible photos/sources enough to choose THE. 1.7 Put your cup down on the arm of your chair. An armchair has two arms. But by using OF the question 'Which one?' is pre-empted. 1.8 The boyfriend of my sister. 1.9 The man who sold the world. 2.0 They're interviewing the man who mows her lawn. ...And so on and so forth...All these examples are defined but not everyone took a definite article. My question is where to find an exact blueprint on how not to mess up with it.