The Tower of London is a medieval castle and fortress 1) ... the centre of England's capital, London. It was built very long ago, in the 2) century. The Tower of London was used for lots of different purposes in the past. 3) was a royal residence, an observatory, an exotic zoo, and even a prison! Today the Tower is a museum. Probably, the 4)... attraction of the museum is the Crown Jewels. They include several crowns that the monarch 5)... for different ceremonies and events.

1) В центре
To answer the first blank, we use the preposition "in" because it indicates the location of the Tower of London. We use "in" to show that something is inside or within a specific area or place.

2) XIII (тринадцатый) century
In the second blank, we need to provide the century in which the Tower of London was built. The sentence says "very long ago," which implies that it is an old structure. Since the Tower of London was built during the medieval period, we can say the 13th century. The medieval period in England spanned from the 5th to the 15th century, so the 13th century falls within that range.

3) It
In the third blank, we need to refer back to the Tower of London. The options given are "he," "she," and "it." Since the Tower of London is an object and not a person, we should use the pronoun "it."

4) Main/greatest
To fill in the blank, we can use words like "main" or "greatest" to describe the most significant attraction of the museum. The sentence mentions that the Tower is a museum, and the most famous part of the museum is the Crown Jewels. Using words like "main" or "greatest" emphasizes the importance or popularity of the attraction.

5) Uses
In the fifth blank, we need to choose the correct verb that matches the subject "monarch." The sentence states that the monarch uses the crowns for different ceremonies and events. The appropriate verb that matches this is "uses."

Overall, the completed paragraph says:
The Tower of London is a medieval castle and fortress in the center of England's capital, London. It was built very long ago, in the thirteenth century. The Tower of London was used for lots of different purposes in the past. It was a royal residence, an observatory, an exotic zoo, and even a prison! Today, the Tower is a museum. Probably, the main attraction of the museum is the Crown Jewels. They include several crowns that the monarch uses for different ceremonies and events.