Question

Age Nouns, pronouns and determiners We use age as a noun to refer to how many years someone has lived:She looks a lot younger but she is actually the same age as me.At the age of … is a common expression:He started to play golf at the age of three.The two sisters started their careers as teachers at the ages of thirty and thirty-three.Warning: We don’t say in the age of when we refer to people’s age:Children normally start school at the age of five.Not: Children normally start school in the age of five.When we talk about someone’s age, we use of age or old. Of age sounds more formal than old:He is a fully qualified pilot and is only twenty-five years of age. (more formal)He is a fully qualified pilot and is only twenty-five years old. (less formal)When asking direct questions about someone’s age or the age of a thing, we don’t normally use age. We say How old …?How old are you?Not: What is your age?How old is your car?Not: What age is your car?We only use What age …? in more formal situations:What age was the child when she first showed signs of the illness?Age or ages can also be used to mean ‘a long time’, or a specific long period in history:It seems an age since we last saw them.During the Ice Age, the whole of Britain was covered in a sheet of ice.I waited for them for ages but they must have forgotten about the meeting.We say the Middle Ages to refer to the period of European history from about the sixth to the sixteenth century AD:Life in the Middle Ages was very hard for most people.Not: Life in the middle age …Middle age and middle-aged refer to a person’s life from the ages of about 40 to 65:Middle age is the most prosperous time of life for many people.Many middle-aged people go to keep-fit classes.

Accepted Answer

https://dictionary.cambridge.org/grammar/british-grammar/age about nouns

Topic	Age
Source	https://dictionary.cambridge.org/grammar/british-grammar/age
Section	Nouns, pronouns and determiners
SubSection	about nouns
Content	We use age as a noun to refer to how many years someone has lived: She looks a lot younger but she is actually the same age* as me.* At the age of … is a common expression: He started to play golf at the age of* three.* The two sisters started their careers as teachers at the ages of* thirty and thirty-three.* Warning: We don’t say in the age of when we refer to people’s age: Children normally start school at the age of* five.* Not: ~~Children normally start school in the age of five~~. When we talk about someone’s age, we use of age or old. Of age sounds more formal than old: He is a fully qualified pilot and is only twenty-five years of age. (more formal) He is a fully qualified pilot and is only twenty-five years old. (less formal) When asking direct questions about someone’s age or the age of a thing, we don’t normally use age. We say How old …? How old are you? Not: ~~What is your age?~~ How old is your car? Not: ~~What age is your car?~~ We only use What age …? in more formal situations: What age was the child when she first showed signs of the illness? Age or ages can also be used to mean ‘a long time’, or a specific long period in history: It seems an age* since we last saw them.* During the Ice Age, the whole of Britain was covered in a sheet of ice. I waited for them for ages* but they must have forgotten about the meeting.* We say the Middle Ages to refer to the period of European history from about the sixth to the sixteenth century AD: Life in the Middle Ages* was very hard for most people.* Not: ~~Life in the middle age~~ … Middle age and middle-aged refer to a person’s life from the ages of about 40 to 65: Middle age is the most prosperous time of life for many people. Many middle-aged* people go to keep-fit classes.*

Age Middle Refer Life Years Started Don’t Children