that后面是对make sure的解释和补充,也就是说,知道这是个定语从句的话,that后面的就是make sure的定语,换句话说,make sure就是主语,这句话可以写成To make sure(主语)(that children under 14 can not seat in the front unless)修饰主语 will be the driver's responsbility
(to make sure that children under 14 can not seat in the front unless。。。) will be the driver's responsbility .
应该是从句做主语吧。然后用it作形势主语代替括号里的句子
不对,把that从句去掉,to make sure will be the driver‘s responsibility仍然是完整的句子
但如果把to make sure去掉,整句话就有问题了,就变成that children……will be responsbility ,无论从语法还是意思都不对了
分析句子成分最直接的方法就是把某一部分去掉后看看还是不是完整的句子