How do i end a formal letter to a teacher?

If one writes logically, he will prove his point. is this sentence correct or contains an unwarranted shift in person?

Pls due today which excerpt from the text most effectively demonstrates that the narrator's point of view about the cabuliwallah has changed? "i felt a little sorry, and would have called him back, but i found he was returning of his own accord." "i sent for mini immediately from the inner apartment. many difficulties were raised, but i would not listen." "tears came to my eyes. i forgot that he was a poor cabuli fruit-seller, while i was—. but no, what was i more than he? he also was a father." "i took them and was going to pay him, but he caught my hand and said: "you are very kind, sir! keep me in your recollection. do not offer me money! —"

Which persuasive technique is used in the passage below? after seeing ads for greasy french fries, sugary soft drinks, and salty chips, you head to the kitchen to fix yourself an enormous (and unhealthy) snack. with the tv blaring in the background, you then waste hours on the web.