Tom is my good friend. He is very clever and we often play games together.

She is my best friend. We always have fun together and she is always helpful when I need her.

My classmate's name is Lily. She is very friendly and helpful, and she loves reading books.

这些句子简洁明了，适合四年级学生的英语水平，并且能够有效地描述一个人的特点和友谊。