【题目】The old rules have to be _____because they only applied to the circumstances that existed when they were made a hundred years ago.
A.developed
B.established
C.observed
D.revised

【答案】D
【解析】句意：老的规则需要被修改因为它们只适合一百年前的状况。A.develop“培养，发展”；B.establish“建立”；C.observe“观察”；D.revise“修改”。根据句意，选D。