HELP ME PLZ

Explain the difference between do vs does like: do something do this does something do this

In his adaptation of this excerpt, laurence olivier uses high cliffs as a a background and he holds onto a knife. what's effect do these choices have?

Aman lives on the twelfth floor of an apartment building. every morning he takes the elevator down to the lobby and leaves the building. in the evening, he gets into the elevator, and, if there is someone else in the elevator -- or if it was raining that day -- he goes back to his floor directly. otherwise, he goes to the tenth floor and walks up two flights of stairs to his apartment.