The girl said how to answer a few words after waiting for so long.

I'm sorry to have kept you waiting so long. I realize that I have neglected, and I will pay attention to it in the future. The answer to this sentence not only expresses the apology, but also the determination to improve, which can make girls feel your sincerity and attitude, give a promise, and ensure that they will reply to your information in time and keep the communication smooth.