1. She's in her early twenties. (=20-23 years old) 2. He's in his late thirties. (=37-39 years old) 3. She just turned six. 4. Act your age! (use this when an adult is being immature, acting like a child) 5. I'm not as young as I used to be. 6. I'm not over the hill yet! (over the hill = an informal expression to say "old") 7. He's no spring chicken. (= he's not young) 8. She's wise beyond her years. (she is young, but she has the wisdom of an older person) 9. I'm having a senior moment. (= I'm being forgetful) 10. He lived to a ripe old age. (= a very old age)