关于it做形式宾语的问题

关于it做形式宾语的问题形式宾语it所指代的真正宾语有3种情况：1,不定式2,动名词短语3,that引导的宾语从句.其中不定式和动名词短语可以互换对吗?比如:He felt it important learning English well.可换成He felt it important to learn English well.那么如果包含形式宾语it的1句话换成宾语从句形式,也可以把不定式换成动名词吗?比如It's important to learn English well.可换成It's important learning English well.最好讲明理由.thanks!形式宾语it所指代的真正宾语有3种情况：不定式2，动名词短语3，that引导的宾语从句.其中不定式和动名词短语可以互换对吗?比如:He felt it important learning English well.可换成He felt it important to learn English well.那么如果包含形式宾语it的1句话换成宾语从句形式,也可以把不定式换成动名词吗?比如It's important to learn English well.可换成It's important learning English well.最好讲明理由.thanks!