Is it okay to not put preposition after "mad" in this sentence? Like "mad about" or "mad for".
Here, the speaker actually means "... I was just mad [that] we hadn't exchanged phone numbers ... " with the conjunction "that" being omitted while speaking. It is common to omit "that" in speaking or writing. Even with the omission of this conjunction, there is no change to the intended sentence meaning. There is no important conjunction or preposition that is missing in this sentence. However, you can choose to add extra words like "about" or "regarding" based on personal preference, but the verb form and tense must be changed accordingly. Ex: She said (that) she was feeling hungry. Ex: There's no proof (that) aliens exist.