The New Orleans Jazz and Heritage Festival, also called Jazz Fest, is a 10-day cultural feast 21 thousands of musicians, cooks, and craftspeople welcome 500,000 visitors each year.
答案：(A) in which
in which 引導形容詞子句修飾先行詞 feast，表示「在這個盛會中，音樂家、廚師、工匠們歡迎50萬名遊客」。such that／as many as／in order for 都不是能引導修飾 feast 的關係詞結構。
本題大考中心未公布逐題答對率，以下不談數據，只談觀念。
空格前面是 feast、後面接著一整句話，很容易先想到 which 那一類的關係詞；但選項裡沒有單獨的 which，四個都是兩三個字組成的東西，一時不知道從哪裡下手，只好挑讀起來最順的 such that。
先看空格後面那一串是什麼：thousands of musicians, cooks, and craftspeople welcome 500,000 visitors each year（數以千計的音樂家、廚師、工藝家每年迎接五十萬名遊客）——主詞是 thousands of musicians...，動詞是 welcome，受詞是 500,000 visitors，主詞受詞都齊了，是一個成分完整的句子。這一步最關鍵：成分既然不缺，就沒有位置留給關係代名詞，which、that 這一類進不來。同一份試卷第 18 題正好相反，那一格後面的 contained alcohol 少了主詞，所以要填 which；兩題擺在一起看最省力。那麼前面的 feast 與後面這個完整句子要怎麼接？答案是介系詞加關係代名詞：in which 等於 in the feast，補上介系詞之後，feast 就以「地點」的身分回到子句裡。把先行詞搬回去驗算一次：Thousands of musicians, cooks, and craftspeople welcome 500,000 visitors in the feast.（在這場盛會裡，數以千計的音樂家、廚師、工藝家迎接五十萬名遊客。）句子完整，介系詞 in 也用得上。in which 在這個位置等於關係副詞 where，兩種說法都通行。
in order for 後面要接「某人 ＋ to ＋ 原形動詞」（in order for us to finish on time 為了讓我們準時完成），但空格後面的 welcome 是沒有 to 的原形，形態就對不上；such that 表示「如此……以致於」，前面要先說出一個程度或性質才接得下去，這一句只是在描述盛會的內容，沒有程度可言；as many as 後面要接數字（as many as 500,000 visitors 多達五十萬名遊客），它修飾的是數量，不是用來連接兩個句子的。三個選項都不是「能把一個完整句子掛回前面那個名詞」的東西。
in which（介系詞加關係代名詞，在這個位置等於 where）、cultural feast（文化盛宴）、as many as ＋ 數字（多達……）、in order for somebody to V（為了讓某人做某事）、welcome（迎接）、craftspeople（工藝家，單數是 craftsperson）
Jazz is not only an American art form but also an international phenomenon. The New Orleans Jazz and Heritage Festival, also called Jazz Fest, is a 10-day cultural feast 21 thousands of musicians, cooks, and craftspeople welcome 500,000 visitors each year.
The main events include unforgettable music on 12 stages, delicious Louisiana cuisine in two large food areas, and crafts artisans from the region and 22 the world purchasing and selling their works. The evening concerts 23 different locations during the 10-day Festival.
The Festival 24 the indigenous music and culture of New Orleans and Louisiana, so the music encompasses every style associated with the 25 and the state: blues, R&B, gospel, Cajun, Afro-Caribbean, folk, Latin, rock, rap, country, bluegrass and everything in between. And of course there is lots of jazz, both contemporary and traditional.