题目

When traveling in England, here are some things to keep in mind. When taking the underground in England, once on the underground train，stand clear of closing doors. They can give you a pretty hurtful knock if they hit you. When getting on or off the tube train, make sure you mind the gap (间隙)! This varies from a few inches to a foot at some of the stations. The saying that English food is boring and tasteless isn’t true, at least not anymore. You’ll find a huge variety (种类) of international restaurants and foods, especially in London. Make sure you eat some of the old-fash一个单位有职工160人，其中业务人员96人，管理人员40人，后勤服务人员24人，为了了解职工的收入情况，要从中抽取一个容量为20的样本，如何去抽取？