描述一个人的眼睛在英语作文中可以通过以下几种方式来表达：

直接描述眼睛的颜色

What color are his eyes？

描述眼睛的特征或状态

His eyes are bright and twinkling.

She has deep brown eyes with a warm smile.

His eyes are sharp and attentive.

使用比喻或形象化的语言

His eyes are like shining stars.

Her eyes are as blue as the sky.

描述眼睛的表情

His eyes light up when he hears good news.

Her eyes show sadness when she thinks about her hometown.

结合其他身体特征

He has a pair of kind eyes that always make me feel safe.

Her eyes are small but very expressive.

通过这些方法，你可以生动地描述一个人的眼睛，使其在英语作文中更加形象和生动。