They periodically stopped their conversations to switch tables so the insights and ideas might 13 and deepen.
答案：(A) circulate
circulate 是「流通、傳布」，本句指與會者換桌讓見解與想法得以流通並深化；emphasize（強調）、recover（恢復）、preserve（保存）語意都不合。
答對率 29%。
circulate 你第一個想到的是生物課的「血液循環」（Blood circulates through the body.），侷限在「繞圈流動」的畫面，沒把它延伸到抽象事物上——消息、想法、文件都可以 circulate，意思是「傳開、流通」。
前半句 They periodically stopped their conversations to switch tables（他們不時中斷談話、換到別桌）已經把機制講明白了：人換桌，想法就跟著跑到別桌去。這正是「流通」。而且空格與 deepen 由 and 並列——circulate 管「廣度」（傳得更開）、deepen 管「深度」（談得更深），一橫一縱，語意正好互補。
下一句 As they moved from one table to another, they noticed new ideas emerging from the discussions.（他們從一桌換到另一桌時，發現討論中不斷冒出新想法）——換桌帶動想法流動，作者等於把答案再講了一次。
emphasize（強調）與 preserve（保存）都是及物動詞，後面需要受詞，本句空格後直接接 and deepen，句構不合；recover 是「恢復、復原」，想法並沒有生病或遺失。
circulate（流通、傳開）、circulation（發行量、循環）、rumors circulate（謠言流傳）、circulate a memo（傳閱備忘錄）、deepen one's understanding（加深理解）。
In 1995, a group of business and academic leaders met at the home of Juanita Brown and David Isaacs in Mill Valley, California. None of them had any idea they were about to create a social innovation that 11 rapidly around the world.
The group was supposed to have a large-circle discussion in their beautiful garden. Unfortunately, it started pouring. With their plan 12 by the rain, the two dozen participants squeezed into the living room. They broke into small, intimate table conversations, recording their insights on paper tablecloths. They periodically stopped their conversations to switch tables so the insights and ideas might 13 and deepen. As they moved from one table to another, they noticed new ideas emerging from the discussions. This in turn enriched subsequent rounds of conversation.
Over the course of the morning, the innovative discussion process 14 a new form of collective effort that transformed the depth, scope, and quality of their discussion. The World Café was 15 created. Since that rainy morning in Mill Valley, the World Café approach has been applied to multi-group discussions and cooperative actions by businesses, industries, and educational institutions around the world.