老师，请看此句：

He was pushing his great head in through the mouth of the cave.

请老师帮我分析一下这句话的结构，谢谢！

     【答】He 是主语，was pushing 是谓语动词（过去进行时），his great head 是 was pushing in 的宾语，push in 是短语动词；through the mouth of the cave 是介词短语，意思是“穿过洞口”、“从洞口”。全句的意思是：“他正在从洞口把他的大头塞进去。”