虚拟啊,就是 shoul + 动词原型或者是直接动词原型.本题是与现在事实相反的虚拟,即,动词用过去式,而be动词都是用were.
具体你看下：
1.辨别if 引导真实条件句和if引导的虚拟条件句的区别
If he has time,he will go with us.= Probably he has time and will go with us.
If he had time,he would go with us.=But in fact he has no time.
2.虚拟条件句中主句和从句的谓与动词构成形式如下表
\x09if条件句中的谓与动词\x09主句的谓与动词
与现在的事实相反\x091.行为动词用did 形式
2.be动词用were\x09Should/would/could/ might + 动词原形
与过去的事实相反\x09had + done\x09 Should/would/could/ might + have + done
与将来的事实相反\x091.行为动词用did
2.should + 动词原形
3.were to + 动词原形\x09 Should/would/could/ might + 动词原形
希望对你有用