What is the one key element every story must have?
Every story must include at least one main conflict. The conflict can be a problem the protagonist must solve, a desire he wishes to fulfill, or an obstacle he strives to overcome. All other elements of the story are connected to the conflict, including the theme and climax.
What factors contributed to the spread of the Black Plague in 14th-century Europe?
Unfortunately, not much was known about hygiene or the spread of disease at that time. Although poor hygiene certainly contributed to the spread of the plague, the disease was largely spread through rats bitten by infected fleas that carried the disease. Infected rats boarded ships that traveled throughout Europe and brought the plague with them wherever they went.
How can a person determine whether to use "Who" or "Whom?"
"Who" functions as a subject. Use it where you would use another subject pronoun, like "he." (For example, you could say, "He went to the store," or "Who went to the store?") "Whom" functions as an object. Use it where you would use another object pronoun, like "him." (For example, you could say, "I am going to the store with him," or "I am going to the store with whom?")