问题 曹老师麻烦再帮我解一下疑惑

It is fun to do /it is fun doingit is dufficult to do /it is difficult doing it is hard to do /it is hard doing it is easy to do / it is easy doing it is nice to do /it is nice doing 等等这种类似的句子，接不定式和动名词的区别到底在哪里？之前我以为跟时态有关，但...

问题 序数词后的to do 不定式

之前语法书上说序数词后的to do 不定式必须是主动形式。但是在阅读中遇到一个句子，Wale is the first country to be joined to the Kingdom of England. 此处的被动怎么解释吗？

问题 appear to have done 和appear to do 的区别

原句：A desire to sell gold appeared to have been worsened by thinking that concerns about the Greek economy have somewhat eased. 此句中可以用appear to be 吗？Appear to have done 和appear to do 有何区别？谢谢老师精彩解答。

问题 as if to do sth 与 as if doing sth 的区别

The man we followed suddenly stopped and looked as if _______ whether he was going in the right direction.( A )A.to see     B.seeing     C.to have seen    D.having seen这道题为什么选A而不选B？我选B的理由是这个人当时正在查看是否走对了...

问题 分析句子结构

I had worried myself sick over Simon’s mother coming to see me. 高考完型中的第一句。不较真的话自己翻译是没什么问题。但是不知道怎么去理解这个句子的结构，也就是说，我如果想以后自己也写出一样的句子，没理解的话是没有办法的...

问题 l hope for a rich life in the coming year.这里的in介词短语修饰哪个

I hope for a rich life in the coming year.这里的in the coming year是修饰life嘛？

话题 know to do sth

话题 be supposed to do

话题 the first to do

话题 be able to do

话题 fail to do sth

话题 know how to do

话题 get to do sth

话题 be positioned to do

话题 be difficult to do