To learn swimming well,one needs much practice.哪个是主句,哪个是从句,怎么判断?

问题描述:

To learn swimming well,one needs much practice.哪个是主句,哪个是从句,怎么判断?
到底有没有从句?这句句子算不算主从句?

这里没有从句.只有一个句子:one needs much practice.其中to learn swimming well只是一个表示目的的状语.目的的状语不能算从句吗?那从句的定义是什么?从句的话必须是个完整的句子,必须要具备主语和谓语。而to learn swimming well只是个动词不定式,既没有主语也没有谓语。这样是否明白?to learn 不是不定式作主语吗?to learn swimming well这个结构没有主语也没有谓语,整体都是个动词不定式。这里不属于不定式作主语的情况。怎样判断不定式是不是做主语?作主语的话是属于句子的主*分,比如这个句子To learn swimming well,one needs much practice. 其中主语是one,谓语是needs,宾语是much practice。那么to learn swimming well在这里明显不是主要成分,只是做状语,表目的。如果句子是To learn swimming well needs practice.则主语是to learn swimming well,谓语是needs,宾语是practice.这样讲明白了没?