The agent was very helpful. We spoke to him.
The agent (THAT / - ) We spoke to was very helpful
The lemonade was refreshing. We ordered that lemonade.
The lemonade (- / THAT) We ordered was refreshing
The dish was delicious. I order the dish.
The dish (THAT / -) I ordered was delicious
The flight departed very late. We had to take the flight.
The flight (THAT / -) We had to take departed very late.
The hotel was really awful. We stayed in for 1 day.
The hotel (THAT / - ) We stayed in for 1 day was really awful
This is the interesting yellow book. I bought it yesterday
This is the interesting yellow book (-/THAT) I bought yesterday.
The airplane seat was not very comfortable. I was assigned that seat.
The airplane seat (THAT / - ) I was assigned was not very comfortable.
The doctor wasn't working. I was expecting to see him
The doctor (THAT / - / WHOM) I was expecting to see wasn't working