单选题
[2005.4]It was long supposed that the main difference between animals and plants was that the former could move about while the ________could not.
A.other
B.latter
C.another
D.later
正确答案：B
答案解析：本题考查固定词组。the former…the latter……表示“前者…后者…”的意思。句中it做形式主语，真正的主语是the main difference between …could not。句意为：一直以来，人们认为动物和植物之间最大的不同就是前者可以走动而后者不能。