def pretty_duration(seconds):
    """Return a human-readable string for the specified duration"""
    
    if seconds < 2:
        return '%d second' % seconds
    elif seconds < 120:
        return '%d seconds' % seconds
    elif seconds < 7200:
        return '%d minutes' % (seconds // 60)
    elif seconds < 48 * 3600:
        return '%d hours' % (seconds // 3600)
    else:
        return '%d days' % (seconds // (24 * 3600))