Be + 宾语 I am a student.
Be + 形容词 I am late.
Be + 介词 I am in my room.
Be + 动名词 I am writing a letter.(现在进行时)
Be + 过去分词 I am needed at the office.(现在被动语态)
Be + 宾语 I am a student.
Be + 形容词 I am late.
Be + 介词 I am in my room.
Be + 动名词 I am writing a letter.(现在进行时)
Be + 过去分词 I am needed at the office.(现在被动语态)