It's natural that she should do so.

It's natural that she should do so.

她这样做是很自然的。 真不明白，直接she do so,就行了，为什么要有should,加上了，有什么意思呀？不加也已是她这样做的意思了啦，why?
即加should与不加should有何分别!?

It's mix ?? It's about It's time... it's time It's raining it impossible和it's impossible I think it's right ,( )it? it's fun 还是it 's funny it's是否等于it is 或it was It's All Vain