很难判断他到底多大岁数。 It was difficult to tell his exact age.
你不应该把香烟卖给没到岁数的青少年。 You shouldn't sell cigarettes to teenagers who are under age/to under-age teenagers.
我提醒过她检查一下交申请表的日期，可她总以为自己最懂。好了，现在她完了，因为明年这时候她的岁数超过了，没资格申请补助金了。 I warned her to check the date her application form should he in, but she always know best. Well, she's cooked her goose now, because by this time next year she'll be too old to qualify for a grant.