You can also compare to words like it, thing, she, he, and equations to definite descriptions. "I don't know who she is." "The culprit was wearing a red coat.

You can also compare to words like it, thing, she, he, and equations to definite descriptions. "I don't know who she is." "The culprit was wearing a red coat." "The mystery number plus 3 is equal to 5." "I'm thinking of a number, but I'm not going to tell you what it is. But I will tell you that if I multiply it by 3, and then subtract 5, I get 1."