几道英语选择能帮忙解释一下吗

Question

It was an unpopular decision to postpone_the new school 这里为什么要用building?
The population of scotland was eight times as large as that of cornwall。 that代指的是什么 those it this为什么不能选
_________,he would have been fired. if he has lied to the boss怎么不对？为什么是Had he lied to the boss ？
Mr johnson must have come back yesterday 怎么用了didn't he 而不是mustn't?

Answer 1

1. postpone doing sth. 推迟做某事
2. that 指代population. 英语语法规定，遇到不可数名词，必须使用that代替。又如：
The weather in Beijing is cooler than that in Guangzhou.
3. if he has lied to the boss 是现在完成时，与后面的would have been fired 对不上，因为后面是虚拟语气。Had he lied to the boss = if he had lied to the boss. 这是与过去事实相反的虚拟语气，套用了句型：If I had done sth, I would have done sth.
4. 表示推测的单词must, 不参加反义疑问。句中yesterday决定反义疑问时用过去时。

Answer 2

1. building - postpone doing 推迟做。。。
2.that 指代 population
3.可以是：If he had lied to the boss, he would have... 虚拟语气 从句 had+过去分词
省略if - Had he lied to ...
mustn't = “一定不能”， 这里是 “没有”

Answer 3

1.postpone后面要加动词的ing形式
2.that 指的是the population
3.这个句子是虚拟语气，所以用Had he lied to the boss
4.因为这个句子的时间状语是yesterday,所以用didn't he

希望对你有帮助！

Answer 4

1.Postpone 是推迟拖延，后面要接动词的ING形式。
2. that 指代前面population。替代一般都用that， 复数要用those。 this 和it 不能用。
3.对过去的虚拟要用过去完成时态，Had...是省略IF的形式。
4.这是对虚拟的否定，Must have done 是对过去某种动作的虚拟肯定，反义疑问句要回归到对过去那个动作的否定疑问。主要区别Must在这里不是使役动词要当做虚拟。