Since his promotion, he's been full of himself, rarely acknowledging his team's efforts.

been 是 be 动词的过去分词形式，在这里构成现在完成时态。 full 的本义是"满的、充满的"，在这里表示"完全沉浸于某种状态"。 of 是介词，表示"关于、属于"的关系。 himself 是反身代词，指代主语"他"自己。 full of himself 是一个固定短语，字面意思是"充满他自己"，引申为"自以为是、自负"的意思，形容一个人过分关注自己而忽视他人。