Then, almost 26 at a given signal, the group begins to march toward the colony 27.
答案：(A) as if
【句型】as if 字詞搭配「彷彿/好像」，表示「幾乎好像在一個既定信號下」，形容螞蟻們同步行動的樣子；even though（儘管，轉折不合）、in case（以防）、such as（例如）都不合。
本題大考中心未公布逐題答對率，以下不談數據，只談觀念。
四個選項的功能差很遠（彷彿、儘管、以防、例如），但如果沒讀出這一句在描寫「整齊得不可思議」，會不確定該放哪一種邏輯關係。
四個選項都是連接性的片語，可見這一格考的是語意。先把整句讀完：Then, almost ___ at a given signal, the group begins to march toward the colony to be raided.（接著，幾乎……收到了某個訊號一般，這群螞蟻開始朝要襲擊的蟻穴前進。）關鍵在 almost（幾乎）——它在提示「並不是真的有訊號，只是看起來像」，所以要填一個表示「彷彿、好像」的說法，答案是 as if。as if 後面除了接子句，也可以接介系詞片語或分詞（He stood there as if in shock. 他站在那裡，彷彿受了驚嚇。），本題接的正是 at a given signal 這個介系詞片語。再用前後文驗算：前一句說螞蟻在巢外集結，這一句說牠們同時開始行進——整齊到讓人以為有人下令，這正是 almost as if 要傳達的效果。
even though（儘管）：表讓步，要求前後互相牴觸，但這裡沒有牴觸。in case（以防萬一）：帶出預防性的條件，與描寫動作的整齊無關。such as（例如）：後面要接舉例的名詞，而 at a given signal 不是「訊號」的例子，是一個比喻。
as if（彷彿、好像）、as though（彷彿）、at a given signal（在某個訊號下）、march toward（朝……前進）、an assembly of（一群……的集結）、a slave raid（擄奴的突襲）。
Some species of ants keep slaves. Probably the best known for the practice is the large brownish-red Amazon ant. A slave raid starts with an assembly of the Amazon warriors outside their own nest. Then, almost 26 at a given signal, the group begins to march toward the colony 27.
When the Amazons reach the nest of their intended victims, a fierce battle may take place. The Amazons fight on 28 they seize the pupae of the raided nest. They carry these back home. In time the pupae develop into adults and spend their lives working for the Amazons.
The Amazons are completely dependent on their slaves 29 their sharp jaws, so well suited for fighting, are useless in taking care of larvae or for digging. Also, the masters become so lazy that, after a while, they lose their muscles, and they become too weak 30 to feed themselves. Finally, they become so unhealthy that they die.