In recent years, the postal service has suffered tens of billions of dollars in losses 19 the increasing popularity of the Internet and e-commerce.
答案：(B) with
【介系詞】losses with the increasing popularity... 表示「隨著網路與電商日益普及而產生的虧損」，with 在此表伴隨關係。at／under／between 皆不符合此處慣用搭配。
with 這個字，你的印象大概只有「和……一起」與「用……工具」這兩種，不太會想到它後面接的可以不是同伴也不是工具，而是一個正在變化的現象。
答對率不到五成，鑑別度只有 30。這一題難，卻連高分群考生也常失手，原因就在 with 的這個用法平常很少被單獨拿出來教：對「和……一起」「用……」這兩個常見義越熟的人，越會覺得四個選項沒有一個對得上，最後憑感覺挑一個。先看空格前後的關係：前面是郵政署近年虧損數百億美元，後面是網路與電子商務日益普及——兩件事同時在發生，而且後者正是前者的背景與成因。劍橋 English Grammar Today 的 with 條目收了「因為、由於」這個義項（例句 With all this work, I'd better stay in tonight.），後面接的名詞若本身表示變化，中文就順成「隨著……」。填進去讀成 has suffered ... losses with the increasing popularity of the Internet（隨著網路日益普及而蒙受虧損）。這一型後面常接 the increasing popularity of、the rise of、the development of 這類講變化的名詞組。
at 後面接的是時間點或地點（at that time、at the station），接不上一個持續變化的現象；under 講的是「在……之下」的狀態或條件（under pressure、under the new law），這裡不是在說虧損發生在什麼規定之下；between 需要兩個拿來相比的東西（between A and B），句中的 the Internet and e-commerce 雖然有 and，但整組是一個名詞組，不是相比的兩端。
with ＋ 名詞（因為、由於；後接表變化的名詞時譯成「隨著……」）、with the rise of（隨著……的興起）、suffer losses（蒙受虧損）、tens of billions of dollars（數百億美元）、under pressure（承受壓力）、e-commerce（電子商務）。
The U.S. Postal Service has been struggling financially for some time. It plans to stop delivering mail on Saturdays, 16 Aug. 1 this year. This decision was announced on Wednesday without congressional approval. 17 forbidden to do so by the Congress, the agency for the first time will deliver mail only Monday through Friday. It is expected that this 18 will save about $2 billion a year.
In recent years, the postal service has suffered tens of billions of dollars in losses 19 the increasing popularity of the Internet and e-commerce.
The postal service plans to continue Saturday delivery of packages, which remain a profitable and growing part of the delivery business. Post offices would remain open on Saturdays 20 customers can drop off mail or packages, buy postage stamps, or access their post office boxes. But hours would likely be reduced at thousands of smaller locations.