这句话的逻辑主语是谁it is impossible for lost time to be made up

这句话的逻辑主语是谁it is impossible for lost time to be made up Henry was happy to hear it.如何理解主句主语同时也是不定式结构的逻辑主语?对于这句话 Henry was happy to hear it.如何理解“主句主语同时也是不定式结构的逻辑主语”? When ------- this city,I want to 这句话mentioned 还是 mentioning逻辑主语是谁? 这句话中主语是谁? It is good for me to do exercise的 逻辑主语是哪个 英语语法老师!形式主语是动词不定式的一种,他也是逻辑主语,可以把他归类到逻辑主语的第一种（不定时的逻辑主语） 那么这句 It is uncertain whether he can come to Jenny’s birthday party or not.也是 When ------- this city,I want to 这句话选什么 A mentioned B mentioning 还有 逻辑主语是谁? it is very easy for you to find a good job这句话真正的主语 It is difficult to learn English well.这句话的主语是什么? 不要发抖,伸舌头,顿脚,这句话的主语是谁 it is no use (persuading) him because he will never change his mind.这里的动名词persuading他的逻辑主语是谁?求分析句子成分,为什么用动名词形式,不要用固定用法概括, heated.water.changes.into.steam这一结构的逻辑主语是主句的主语,这句话是何意,逻辑主语是heated吗...heated.water.changes.into.steam这一结构的逻辑主语是主句的主语,这句话是何意,逻辑主语是heated吗?请高 to be +形容词的用法请问这句话语法怎么分析It is very nice of you to be so considerate.这句话中 to be so considerate 即 to be+形容词是句子的逻辑作主语吗?这句话下面的改写方法对吗？有不妥，忘指教，1 动词不定式,过去分词,现在分词的主语分别是谁?逻辑主语 Once seen ,it can never be forgotten这是一个分词做条件状语从句吧?它的主语是什么?逻辑主语与句子主语一致? 语法书上说：It is + adj./ n.+ for sb to do sth 做某事对某人来说……for sb是不定式的逻辑主语,to do sth是不定式做真正的主语,而it只是形式主语逻辑主语不就是形式主语吗?怎么for sb和it都是形式主 It has been a long time since i saw you last time.这句话的形式主语是it?那么它的真正主语是什么?如：It is a long time between 1900 to 2012.这句话的形式主语是it，真正主语是betweem 1900 to 2012.Between 1900 to 2012 is 句子作主语的情况?It is strange that he didn't come here yesterday.这句话中那个是主语？