He was about to 19 the dishes, but he noticed that in one dish, the bacteria had failed to grow in the area around the fungus.
答案：(A) toss out
toss out the dishes（把培養皿丟棄）表示弗萊明原本打算把這些受污染的培養皿丟掉，卻意外發現黴菌周圍沒有細菌生長；get off／catch up／carry on 均不符合此處語境。
toss 你的印象大概是擲硬幣、拋球那個「拋、扔」的動作，像 toss a coin，沒把它跟丟垃圾連在一起。toss out 就是把不要的東西扔掉，和國中學過的 throw away 是同一個意思，只是換了一組字。
四個選項都是動詞片語，先從語意線索下手。前一句說他發現有些培養皿長了黴菌，which had ruined his experiment（那毀掉了他的實驗）——實驗既然毀了，接下來的自然動作就是把這些培養皿處理掉。空格後面直接跟著受詞 the dishes，所以這一格要的是能帶受詞、而且意思是丟棄的片語。整句用 be about to V（正要……）帶出來，接著用 but 轉折：正要丟掉，卻注意到異常——這個差一點就錯過的轉折，正是整篇在講機緣巧合的核心。
get off（下車、脫身）與 catch up（趕上、跟上）語意都與丟棄無關，擺在 the dishes 前面也接不順。carry on（繼續進行）形態上帶得了受詞，但意思是把某件事繼續下去，代進去變成他正要繼續那些培養皿，語意不通，而且與後面的 but 轉折接不上——如果他打算繼續做，發現黴菌就不算意外的插曲了。鑑別度 57，分開的是有沒有把前一句的 ruined his experiment 讀進來。
下一句藏著一個高頻考點：a drug that has since saved millions of lives。你學過的 since 後面一定要接東西——接時間點（since 2010）或接子句（since I was a child）；這裡的 since 後面什麼都沒接，夾在助動詞與過去分詞之間，這時它是單獨當副詞用，意思等於 since then（自那時起）。判準就這一句：since 後面不接名詞也不接子句，它就是 since then。同型的句子題庫裡還有兩處——指考 101 年那篇的 security measures have since been tightened（自那時起安全措施已加強）、學測文意選填 113 年那篇的 Phones ... have since been built around the world（自那時起世界各地陸續建起）。學測文意選填 93 年第 36 題考的正是這個字（have since perished），答對率只有一成五，是歷年最低的幾題之一。
toss out（扔掉、丟棄）、throw away（丟掉）、be about to V（正要……）、carry on（繼續進行）、catch up with（趕上）、give rise to（引發、導致）
Scientific discovery can take various forms. One of them is "serendipity," the luck of finding valuable things unintentionally. Serendipity was at work when Alexander Fleming discovered penicillin, the antibiotic miracle.
Fleming had long been known for having an untidy laboratory. One morning in 1928, this 16 proved very fortunate. It was his first day coming back to work after a long vacation. Before the vacation, he 17 in the sink a number of petri dishes in which he had been growing bacteria. While he was sorting through the long 18 dishes of germs that morning, he observed that some of the dishes were contaminated with a fungus, which had ruined his experiment. He was about to 19 the dishes, but he noticed that in one dish, the bacteria had failed to grow in the area around the fungus. This accidental finding gave rise to subsequent research that led to the discovery of penicillin—a drug that has since saved millions of lives.
Chance 20 , however, may not be enough to make key discoveries like this. The scientist must have a prepared and open mind to detect the importance of the unforeseen incident and to use it constructively.