Choose the correct conjunction to show contrast: 'The plan seemed perfect, ______ it failed to consider budget constraints.'
答案解析
核心考点：转折连词辨析。解题思路：前后分句为对立关系，需用but连接。选项分析：B正确，but表转折；A表并列，C表结果，D表原因。易错点：误选and忽略逻辑关系。
正确答案：B