英语 关于含义宾语从句的主动句变被动的问题

我就以你给的句子为例来说明.
They said that he had gone abroad to study English．
在这个句子中he had gone abroad to study English是宾语从句,that 是先行词,是陈述句时用来引导从句的.这个从句在句中充当宾语,宾语一般是由名词或代词.所以,这句话的被动形式就成了 That he had gone abroad to study English was said． 为了是句子各部分均衡,用it 代替从句就变为 It was said that he had gone abroad to study English．
而在英语中,一些表示“据说”或“相信”的动词如believe,consider,expect,report,say,suppose,think等可以用于句型“It＋be＋过去分词＋that从句”或“主语＋be＋过去分词＋to do sth.”.
例如,It is said that the boy has passed the national exam.
＝The boy is said to have passed the national exam.
而你后面的那个句子,He told me the police had arrested the thief,只是把宾语部分变为了被动形式,主句部分没有发生改变,还是He told me .太感谢了，完全明白了。我还想问一下这句 People said that there was gold in that cave 变被动 为什么是变成 there was said to have been gold 变成 there was said to be gold 不行吗？不是很理解这里的have been goldthere was said to have been gold
和你说的
there was said to be gold
这两句区别只在后面的不定式，因为不定式本身含有未发生的，或动作前后相继的意思，而且不定式里只能用动词原形，所以要表示过去时态只能用 to have done 的形式了。那我是不是能这样理解，一旦是过去式，或过完等，就要变成主语＋be＋过去分词＋to have done呢？而不能直接用to do sth比如 people think that they found a book 变成they are thought to have found a book,而不能用they are thought to be find a book。这样理解 对吗？嗯，是这样的。absolutely right！