填空题 This is the {{U}}longest{{/U}} flight I {{U}}have ever taken{{/U}}. By the time we get to Los Angeles, we {{U}}had flown{{/U}} {{U}}for{{/U}} 9 hours. A. longest B. have ever taken C. had flown D. for
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【正确答案】 1、C应改为will have flown。    
【答案解析】[解析] By the time“到……时”，主语应使用将来完成时。