If you don't know a person's last name, use 'ma'am' or 'sir'.
如果你不知道一人的姓, 你应称呼他为 'ma'am' 或 'sir' 。
The nomads who made these markings lived by hunting and fishing during the last Ice Age which began about 35,000 B.C.and ended about 10,000 B.C.
这些痕迹是游牧人留下的,他们生活在从公元前约35,000年到公元前10,000年的冰川期的末期,以狩猎、捕鱼为生。