Most students stay at school until they are 16 or 17.大多数学生都继续上学,直到十六七岁左右。Some of the prisoners were only 16 or 17, and they looked scared to death.有几个囚犯才十六七岁—他们看上去吓得半死。He procured girls of 16 and 17 to be mistresses for his influential friends.他介绍了些十六七岁的女孩给他那些有权势的朋友当情人。