Put a question to each sentence
1) She had shown us the central part of the city by 5 o'clock.(By what time)
2) She had bought all the things for dinner by 12 o'clock. (Наd)
3) By that time they had seen most of the Tower of London. (Had)
4) By Saturday Martin had seen all the most popular places of interest in London. (By what time)
5) By 8 o'clock the daughter had prepared breakfast. (Who)