...and stay clear of coral reefs, sunken ships, fish beds, and other general 20.
答案：(B) obstacles
obstacles（障礙物）呼應前文 coral reefs, sunken ships, fish beds 等具體例子，表示海底電纜鋪設須避開這些障礙物；directions／aquariums／circulations 均不符合此處語意。
四個選項都是複數名詞，文法上都填得進 and other ___。如果只盯著空格看，obstacles（障礙物）與 directions（方向）好像都講得通，aquariums 又因為前面剛出現 fish beds（魚群棲息地）而顯得眼熟。
這一題的線索是 and other 這個結構本身。英文列舉時常用「A, B, C, and other ＋ 概括名詞」收尾，而 other 後面那個名詞必須能把前面列的東西全部收進去。前面列的是 coral reefs（珊瑚礁）、sunken ships（沉船）、fish beds（魚群棲息地），三者的共同點不是形狀也不是位置，而是鋪設電纜時都要避開，所以概括名詞就是 obstacles（障礙物）。句中的動詞 stay clear of（避開、遠離）也把答案框死了，它後面接的必定是該閃開的東西。鑑別度 49，分的是有沒有把 and other 當成「請你找上位概念」的訊號。
directions（方向）不是東西，珊瑚礁與沉船也不能算是方向。aquariums（水族館）是拿前面的 fish beds 做出來的誘答，但水族館是陸地上的人造建築，不會出現在海床上，眼熟不等於正確。circulations 的 circulation 講的是血液循環、空氣流通，或報刊的發行量，與該避開的障礙毫無關係。
stay clear of（避開、遠離）、A, B, and other ＋ 概括名詞（…以及其他…）、an obstacle to（…的障礙）、a coral reef（珊瑚礁）、a sunken ship（沉船）、prevent damage（防止損壞）
When we stream the latest TV series, or download high-resolution photos, we are probably unaware that the data behind them is speeding around the world in cables under the sea.
These cable systems, faster and cheaper than satellites, carry most of the intercontinental Internet traffic. Today, there are over 420 submarine cables 16 , stretching over 700,000 miles around the world. It is not a new phenomenon, 17 . The first transcontinental cable—laid in 1854—ran from Ireland to Newfoundland, and made telegraph communication possible between England and Canada. Currently, the world's highest-capacity undersea Internet cable is a 5,600-mile link between the US and Japan. 18 named "FASTER," the cable connects Oregon in the US with Japan and Taiwan.
The submarine cables require extra 19 to install. They must generally be run across flat surfaces of the ocean floor, and stay clear of coral reefs, sunken ships, fish beds, and other general 20 . The fiber-optic cables are also very fragile, so they are surrounded with layers of tubing and steel to prevent damage.