英语语法：When and where was it that Mr Thomson got such rare fis

英语语法：When and where was it that Mr Thomson got such rare fishes?对于这个句子有几个问题
问1：It was when and where that .
请问这里that从句是什么从句?主语从句?
问2：when where 作表语?

这个应该不是主语从句,而是强调句型.强调句型主谓宾都全了,是个简单句没有从句,it is/was...that都是多余的成分；而主语从句里is/was是主句的谓语.
本句若将It was及 that同时省去为：Mr.Thomson got such rare fishes when and where.句子同样成立,因此是强调句型.When and where 做状语.
两者的区别在于：
强调句将句子中的it is / was …that同时省去,句子仍然成立；而主语从句将that与后面部分代替it,成立,is/was不能省.如：
(1) It is Li Lei’s brother that you met in the street yesterday.你昨天在街上所见到的就是李蕾的兄弟.
本句若将It is 及 that同时省去为：You met Li Lei’s brother in the street yesterday.句子同样成立,因此前面的句子是强调句型.
(2) It is exciting that we have succeeded in sending up Shenzhou V.我们成功地发射了神舟五号这件事情真令人兴奋.
本句若将It is 及 that同时省去为：We have succeeded in sending up Shenzhou V exciting.显然句子错误,因此不是强调句型,而是主语从句.
再问： 根据我理解 强调句里的that为连接代词 为定语从句 虚主语从句里的that就是一个名词性从句 that不充当任何成分。 对不。
再答： 强调句不是定语从句，定语从句里面的that是占从句成分的，而强调句中的that是不占成分的，整句话是个简单句，只不过it is/was... that是强调句的句型。 逻辑主语为it的主语从句里，that是从句的引导词，也不占成分，所以强调句和主语从句的区别不在于that，而在与is/was能不能去掉。
再问： 强调句的that怎么不占成分？that you met in the street yesterday You met that , you met XX's brother 这里that就是宾语，代xx's brother
再答： It is Li Lei’s brother that you met in the street yesterday. 这要是宾语从句，那就得用whom引导而不是that。这是强调句。 宾语从句是这样的：I talked to Li Lei's brother whom you met in the street yesterday. 我建议你去看看专门讲强调句的专题，一定是it is/was...that/who结构的，去掉后能还原成一个简单句的。http://wenku.baidu.com/view/f6d023340b4c2e3f572763d4.html
再问： It was the window that Tom broke last night. --- Tom broke that(the window) last night. that不做成分能成立？ 其实按照你的理解和做法更简单，也不会错，我也不说什么了，以后你会明白的
再答： 我以后会明白？您的话真奇妙。 Tom broke the window last night. 就这么个简单句，你要想强调window，那怎么办？ 就得用强调句型：It was the window that Tom broke last night. 强调Tom: It was Tom who broke the window last night. 强调last night: It was last night that Tom broke the window. 而定语从句是因为一个简单句根本没办法满足需要： I fixed the window. Tom broke the window last night. => I fixed the window which/that Tom broke last night. 您既然对强调句型不愿接受那也就这样吧。能解释的我都写在上面了。