多大

nǐ duō dà nián líng

你多大年龄？

How old are you?

nǐ jiā xiǎo hái jīn nián duō dà le

你家小孩今年多大了？

How old is your kid?

tā bù zhī dào zì jǐ de hái zi duō dà le

他不知道自己的孩子多大了。

He doesn't know how old his kid is.