对比:我是一个学生。我学习英语。 简单句: I am a student. I learn English. 并列句: I am a student, and I learn English. 复合句: I am a student, so I learn English. Because I am a student, I learn English. 非谓语(作状语) Being a student, I learn English. I am a student, learning English. I ,being a student, learn English.