...they were merely 15 but never actually seen in person in the comic strip.
答案：(C) spoken of
spoken of（被談論）與後文 but never actually seen in person（但從未真正露面）形成對比，表示瓊斯一家人只是被提及，卻從未在漫畫中實際現身；checked out（查核）、watched over（看顧）、traded with（與……交易）均不符合此處語意。
四個選項都是「動詞加介系詞」的片語動詞，改成被動之後長得都一樣，放進 they were merely ___ 讀起來也都成句。如果只讀到空格為止就停下來，這一題等於在四個片語裡亂猜。
這一句整個靠 but 前後一正一反鎖死。but 後面是 never actually seen in person（從未真正露面），講的是「用眼睛看到」；那麼 but 前面的 merely ___ 就必須是與「看見」對立、而且分量更輕的一件事，也就是只被人用嘴巴提到，spoken of（被談論）。結構上再驗算一次：speak of sb 是「談到某人」，改成被動時介系詞不能丟，要寫成 sb is spoken of，這與課本教過的 The doctor was sent for.（去把醫生請來了）是同一個機制。鑑別度 59，分的是有沒有把 but 之後那半句讀完再回頭填。
checked out 的 check out，你的印象大概只有旅館「退房結帳」，它也有「查看、借出」的意思，但這幾個意思都不與「露面」對立。watched over（看顧、守護）裡的 watch 本身就是「看」，與後面的 never … seen 語意矛盾，同一句話不會說「他們只是被看著，卻從沒被看見」。traded with（與…交易）與露不露面完全無關。
speak of（談到、提及）、be spoken of（被談論，改被動時介系詞要留在後面）、in person（親自、本人）、merely（僅僅、只不過）、check out（退房結帳；查看；借出）、watch over（看顧、守護）
"Keeping up with the Joneses" is a catchphrase in many parts of the English-speaking world. Just like "keeping up appearances," it refers to the 11 to one's neighbors as a standard for social status or the accumulation of material goods. Generally speaking, the more luxuries people have, the higher their value or social status—or 12 they believe. To fail to "keep up with the Joneses" is thus perceived as revealing socio-economic inferiority or, as the Chinese would put it, a great loss of face.
The 13 was popularized when a comic strip of the same name was created by cartoonist Arthur R. "Pop" Momand. The strip was first published in 1916 in the New York World, and ran in American newspapers for 28 years before it was eventually 14 into books, films, and musical comedies. The "Joneses" of the title were rich neighbors of the strip's main characters and, interestingly, they were merely 15 but never actually seen in person in the comic strip.