`\color{#145277}{N}\color{#246483}{a}\color{#34768F} {e}\color{#44889B}{u}\color{#539AA7}{n}`

`21.`

`->` Only kings and dukes had enough money to buy books.

`=>` Thông tin : "Before printing presses were invented, only rich people like kings and dukes could afford to buy books."

`22.`

`->` Because books were dear and magical

`=>` Thông tin : "They wanted books because they were expensive and there was something magical about them."

`23.` 

`->` They were large and expensive at first

`=>` Thông tin : "The position with computers in  very similar today. A few years ago, computers were very large and expensive"

`24.`

`->` A person who buys a computer knows how to use it

`=>` Thông tin : "Lots of people not only own microcomputers but also know how to use them."

`25.` 

`->` Yes

`=>` Thông tin : "In many countries, however, the situation has now completely changed. Lots of people not only own microcomputers but also know how to use them."