had i realized 和did i realizedonly that time___the importance of english?为什么不可以用had i realized?

had i realized 和did i realizedonly that time___the importance of english?为什么不可以用had i realized?
had i realized 和did i realized
only that time___the importance of english?为什么不可以用had i realized?

had i realized 和did i realizedonly that time___the importance of english?为什么不可以用had i realized?
正常语序是i realized the importance of english at that time..
在那个时候是了解到,不是已经了解到..
主要强调that time 那一个点
而had是对后来造成的影响,如果用had,这句可以是i had .from then(that time) on.

语境问题。