这是什么句型?How could I forget it.

这是什么句型?How could I forget it. how i wish i could see it,然后说明how用法.我看不懂这个句型, Because I forget how to play it. How I wish I could kept it! I could not forget How could i forget she Forget the days that we spent togethe if you forget.how can i keep it how can i forget I went to forget you.but I can't make it.what else could I d 为什么说what fun it is!而不用how fun it is?这是什么句型? how could it How I wish I could have such a kind of friend用了什么句型