When I reached inside the floorboard, my hand touched what felt like a book. I pulled it out. It was

21. A    22. B    23. C
【解析】
这是一篇记叙文。作者碰巧发现一本名字叫Bartlett’s Familiar Quotations的书，作者发现这本书里收集了成千上万人的引语。作者在九年级时，生动地理解了里面人物的感情。
【21题详解】
推理判断题。根据第一段中I pulled it out. It was an old and small book: Bartlett’s Familiar Quotations. I wondered whom the quotations (引语) were supposed to be familiar to.“我把它拿出来。那是一本又旧又小的书:《巴特利特熟悉语录》。我想知道这些引文应该是谁熟悉的。”由此可知，当作者偶然发现这本书时，他觉得“好奇”。故选A。
【22题详解】
细节理解题。根据第二段最后一句He had gathered up quotations from thousands of other people.“他从成千上万的人那里收集了引语。”由此可知，巴特利特惯用的引语主要包括千万人的思想。故选B。
【23题详解】
推理判断题。根据第四段In ninth grade, I worked as an assistant at our local library. I often hid in the comer, where no one would see me, and I would read. It was at this library that I realized how some of those emotions I’d felt while reading Bartlett’s Familiar Quotations came to life in the characters I had started discovering in novels.“九年级时，我在当地图书馆做助理。我经常躲在角落里看书，这样没有人会看到我。正是在这个图书馆里，我才意识到，当我读巴特利特那些熟悉的引语时，我的一些情绪是如何在我开始发现的小说中的人物身上体现出来的。”由此可知，作者在九年级时，他生动地理解了人物的感情。故选C。