You mustn't go too high,or you()dangerous Awill be B are C would be Dis going toWe have known each other(）Asince we were youngBafter we were young Cwhen we are young D if we are young

You mustn't go too high,or you()dangerous Awill be B are C would be Dis going to
We have known each other(）Asince we were youngBafter we were young Cwhen we are young D if we are young

分别为选A 和 A