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21£®Don’t talk to Simon like that. He is only _______ eleven year-old boy£®
    A£®a    B£®an    C£®the D£®²»Ìî
22£®Ricky caught a bad cold yesterday£¬_________he had to stay at home£®
    A£®because    B£®but    C£®or D£®so
23£®When traffic lights are red£¬we ________ stop and wait.
    A£®may    B£®can    C£®must D£®might