Which sentence must be revised to eliminate the preposition at the end?

The museum had the throne where the king sat on.
This is the beach umbrella we will be sitting under.
I missed class, so I asked the teacher what we talked about.
The concert starts at two, so I told him to meet me before.

Read the excerpt from act i of the importance of being earnest. lady bracknell. well, i must say, algernon, that i think it is high time that mr. bunbury made up his mind whether he was going to live or to die. this shilly-shallying with the question is absurd. . i should be much obliged if you would ask mr. bunbury, from me, to be kind enough not to have a relapse on saturday, for i rely on you to arrange my music for me. it is my last reception, and one wants something that will encourage conversation, particularly at the end of the season when every one has practically said whatever they had to say, which, in most cases, was probably not much. what aspect of lady bracknell’s behavior does wilde use to poke fun at the importance placed on frivolous events in formal society? her concern with a party instead of mr. bunbury’s health her interest in playing classical music at her reception her jealousy over algernon’s friendship with the sickly mr. bunbury her concern about the health of algernon’s friend

What is a positive result of the scientific revolution

In a short story the narrator's word choice