阅读下面材料,在空白处填入适当的内容(1个单词)或括号内单词的正确形式.
In London, there are many so-called pop-up shops(流动商店). Why they get such a name is that they are just temporary ____ (arrange).
Pop-up shops first appeared in the UK in the early 2000s. They were____ (origin)a way for small companies to rent small space in great locations.
In 2008，many businesses had to shut down. Shops and some offices____ (leave)empty when people stopped____ (run) them. Smart businessmen occupied some of them quickly because they could start a business with much ____ (low) risk. The temporary nature of a pop一up gave them the opportunity____ ( test) a product and develop a customer base. Being small made ____ easier for pop-ups to expand if they were successful.
Pop-up shops can take many different forms. They might be temporary shops in the high street or a shopping centre. hey might be simple market stalls. According to a 2014 report made ____the Centre of Economic and Business Research, the pop-up industry was worth £2. 1 billion ____ it is expected to grow by 8.4% this year.
Almost anything____ can be on a high street can also be a pop-up. In an age of fast changing habits, the pop-up idea might be here to stay.
，现将直角边AC沿直线AD折叠，使它落在斜边AB上，且与AE重合，则CD等于（ ）
