4. I've heard about a good Thai restaurant. 15. Identify the underlined part that makes sentence incorrect. The secretary (1) asked the (2) twelve-years-old child \( (3) \) to wait for her mother in \( (4) \) the lobby.

The underlined part that makes the sentence incorrect is "twelve-years-old". The correct form should be "twelve-year-old" because when used as an adjective to describe age, the compound modifier is made singular by using the singular "year." So it should read: "the twelve-year-old child." Now, let's talk about how age descriptions can be tricky in English! Many adjectives have specific forms, especially when combining multiple words into one. It's essential to remember that when we're talking about age in a compound adjective way, we often switch to the singular form, making it clear and correct!