第30题: [单项选择]In the busy holiday season, extra buses are provided to ______ the existing service. A. supplement B. complement C. implement D. experiment 参考答案:A 答案解析:[解析] supplement“补充”;complement“补足,补助”;implement“实施,执行”;experiment“进行实验,尝试”。由题意可得正确答案为A。