第23题: [单项选择]The ______ indicator of this stage is the percentage of students who make the transition to college within 1 year of completing high school. A. noticeable B. visible C. principal D. perceptible 参考答案:C 答案解析:[考点] 词义辨析。principal意为“主要的,首要的”,符合句意。noticeable“显而易见的,值得注意的”;visible指“看得见的,明显的”;perceptible指“可察觉的,可感觉