什么是动宾关系?什么是主谓关系?（动宾关系=被动关系吗?,主谓关系=主动关系吗?）例如：
Seen from the top of the hill,the city looks beautiful.
Freed from endless homework on weekends,the students now find their own activities,such as taking a ride together to watch the sunrise.
这两句是动宾关系还是主谓关系?怎么看出?