He saw a man with a hole in the leg of his trousers and 29 realized what Californians 30 for the rough work they were doing—good, strong trousers!
答案：(D) suddenly
語意「突然意識到」，suddenly 符合這種靈光一閃的情境；casually（隨意地）、frequently（經常地）、regularly（定期地）都不符合這個「頓悟」的語意。
本題大考中心未公布逐題答對率，以下不談數據，只談觀念。
四個選項都是副詞，其中三個是頻率副詞（casually 除外的 frequently、regularly），如果沒注意到 realize 這個動詞的性質，會覺得都能擺進去。
四個選項都是副詞，可見這一格考的是語意，而關鍵在它修飾的那個動詞：realized（意識到、領悟到）。realize 講的是一瞬間想通的動作，不是一段可以反覆進行的行為——一個人不會「經常領悟」或「定期領悟」同一件事。所以 frequently（經常地）與 regularly（定期地）這兩個頻率副詞先出局。再看情境：他在咖啡館裡看到一個人褲管破了一個洞，腦中忽然閃過一個念頭——加州人需要的是耐穿的褲子。這是靈光一閃，填 suddenly（突然地）。前一句的 he had an idea（他有了一個點子）也是同一個瞬間，兩處互相印證。
frequently（經常地）、regularly（定期地）：兩個都是頻率副詞，與 realize 這種一次性的頓悟接不起來；而且它們意思相近，依「同義的選項不可能只有一個對」也可以一起砍掉。casually（隨意地、不經意地）：講的是態度隨便，而他這個念頭是關鍵的轉折，不是隨口想想。
suddenly realize（突然意識到）、all of a sudden（突然）、come up with an idea（想出點子）、a hole in（……上的一個洞）、trousers（褲子）、a small town（小鎮）。
When Levi Strauss arrived in the United States from Bavaria, he was only seventeen, poor, and knew very 21 English. Like most immigrants, he was 22 a better life. So, when gold was discovered in the West in 1849, he 23 thousands of others and rushed to California.
24 he planned to open a shop in San Francisco, he took many goods with him, 25 a large quantity of canvas. He hoped to sell 26 as material for tents or wagon covers. Business, however, was not 27 he had expected.
28 , as he sat in a cafe in a small town, he had an idea. He saw a man with a hole in the leg of his trousers and 29 realized what Californians 30 for the rough work they were doing—good, strong trousers!