新概念二册64课,有些句子理解不了,In1858,aFrenchengineer,AimeThomedeGamond,arrivedinEnglandwithaplanforatwenty-one-miletunnelundertheEnglishChannel.（这个好理解）Hesaidthatitwouldbepossibletobuildaplatf

Question

新概念二册64课,有些句子理解不了,
In 1858,a French engineer,Aime Thome de Gamond,arrived in England with a plan for a twenty-one-mile tunnel under the English Channel.（这个好理解）He said that it would be possible to build a platform in the centre of the Channel.（这个好理解）This platform would serve as a port and a railway station.（这句话还是间接引语吗?所以用would,但是前面没有在出现,he said）The tunnel would be well-ventilated if tall chimneys were built above sea level.(这句话是虚拟语气吗,还是间接引语呢.)In 1860,a better plan was put forward by an Englishman,William Low.（这个好理解）He suggested that a double railway tunnel should be built.（这个好理解）This would solve the problem of ventilation,for if a train entered this tunnel,(这句话是虚拟语气吗,还是间接引语呢.)it would draw in fresh air behind it.Forty-two years later a tunnel was actually begun.If,at the time,the British had not feared invasion,it would have been completed.The world had to wait almost another 100 years for the channel tunnel.it was officially opened on march 7,1994,finally connecting Britain to the European continent.

Answer 1

This platform would serve as a port and a railway station.
这个句子不是间接引语里的成分,间接引语在前一个句子中已经完成了,这个句子直是对前一个句子中的platform进行的解释.
The tunnel would be well-ventilated if tall chimneys were built above sea level.
这个句子不是间接引语,因为它首先不是宾语从句.其次,它是一个一般意义上的if条件状语从句,只不过表示的是过去时态.
This would solve the problem of ventilation,for if a train entered this tunnel,it would draw in fresh air behind it.
这个句子也不是虚拟语气或间接引语,同样是一个表示过去意义的if条件状语从句.
总的来说,虚拟语气表示相反的事实或假设,但以上句子都不能体现这一点,因此属于真实条件句.