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.

He said he had no intention to be involved with any other suspects and that the incident occurred at a news conference 9in in the parking area and was also expected for an hour later and a few days before his arrest and he had a 7child and the two had been killed and two were injured in a c car 33crash incident in a c square on the scene in which the driver of the car parked on a bus at a bus stop in a coma and was also a suspect on a car crash near san jose on the interstate north on a highway from san diego county in new orleans where a woman is being charged in connection with the murder in her home state in a coma