Four Freedoms of the EU 歐盟四大自由
Four Freedoms of the EU
繁：歐盟四大自由
简：欧盟四大自由
歐盟所有28個成員國都是歐洲單一市場的成員。它使得成員國在歐盟四大自由原則的基礎上相互自由貿易，即貨物、服務、資本和人員的流通自由。
白墨（2016年10月6日）。焦點：英國脫歐 「硬脫」「軟脫」如何脫。BBC 中文網，取自 http://www.bbc.com/zhongwen/trad/indepth/2016/10/161006_ana_brexot_hard_soft
Four freedoms
Free movement of goods, capital, labour and services is a fundamental feature of the EU, and the EU considers these four freedoms to be indivisible. So if Britain does not agree to unrestricted immigration from the EU, it cannot have unrestricted access to the single market.
Sullivan, C. & Houlder, V. (2017, February 15). Brexicon: your guide to the language of leaving the EU. Financial Times. Retrieved from https://ig.ft.com/brexicon
The European Parliament Office in London held a panel debate earlier this month to a full house on the impact of Brexit on freedom of movement, one of the fundamental four freedoms of the EU.
European Parliament. (2017, May 18). Brexit and the EP: what does it mean for free movement? Retrieved from http://www.europarl.europa.eu/news/en/press-room/20170511AVI74362/brexit-and-the-ep-what-does-it-mean-for-free-movement