18【填空题】As long as it keeps ticking, you will know what time it is. What happens if it is not____or it stops?

根据句意，“it”指钟表。前半句“as long as it keeps ticking”表明钟在正常运行时可显示时间。后半句需填入一词与“stops”并列。综合分析，“accurate”最贴切，表示“准确的”。若填“working”，与“stops”语义重叠；若填“ticking”，则显冗余。完整句子为： “As long as it keeps ticking, you will know what time it is. What happens if it is not accurate or it stops?” 答案：accurate。