如图所示，一束光在空气和玻璃两种介质分界面上同时发生反射和折射，其中____ 是折射光线，反射角等于____ 。

      Apply for a Library Card

    Any person who lives, works or attends school in New York State is qualified to receive a New York Public Library card free of charge.

    Adult and teen users may either apply online or in person at any New York Public Library location. Applications for children aged 11 and under must be completed in person, and require the signature of a parent or guardian.

    When you apply for a card online, you will receive a 7-digit temporary barcode(条形码). This allows you to set a PIN (Personal Identification Number).

After you receive your permanent barcode, which is required to borrow materials, search library databases, or reserve a computer, you must validate your card.

    Renew or Validate Your Card

    All adult, teen and child library cards for cardholders in New York City and areas of New York State outside of New York City expire(期满) and must be renewed every three years. New library card applicants who applied for a card online must validate their card before full cardholder privileges can be extended.

    Cardholders in New York City must visit any New York Public Library location to present the required forms of identification in order to renew or validate their card.

    Cardholders from areas of New York State outside of New York City may email scans or copies of the required forms of identification to patronaccounts@nypl.org.

    Forgot Your PIN?

    If you provide the library with a valid email address, you can click on the Forgot Your PIN? Link on the login(登录) screen of either Biblicisms or the Classic Catalog. A link with instructions on changing your PIN will be sent to the email address on your account, giving you a brief period of time to update your information. You must select a 4-digit numeric PIN, with no repeating or obvious characters(e.g.1234 or 2222).

    If you have not provided us with a valid email address, you have to visit a library location with valid identification to have a staff member reset your PIN for you.

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家书
延叔喝完第一杯酒，雪花就柳絮般飘落下来。菊麻雀似的蹦进门，喊道：“哥来信了。”延叔接过信又递给菊：“快拆开念念。”菊娘一脸惊喜地从灶间跑出，坐到靠墙的矮凳上，认真地仰起头。菊小心地拆开信，抽出薄薄的一张纸。 
“我一切都好，只是钱不够用。春节车上挤，不回家过年了。”菊一字一顿地念出，脸上的喜悦一点点地消失。 
延叔有些不高兴，完了？菊淡淡道，完了。
延叔长长地“嗯”了一声，倒满一盅酒，咕咚喝下。菊娘一看延叔脸色不对劲儿，忙打起圆场：“收到信就好。伢子在大学念书很忙，没工夫写许多话。” 
菊问：“回不回信？”菊娘斜瞟一眼：“当然回。把家里事告诉哥，让他安心念书。” 
菊趴到桌子上，从书包里翻出两张草稿纸，红通通的小手一把撰住笔杆裂开的圆珠 笔。延叔叹了一口气说：“告诉你哥，信已收到，钱过几天凑好寄去。叫他放心。”说完回过头去，“我没什么说了。”菊娘心领神会，双手拢到围裙下，脸上漾出笑容：“我说两句。对哥说家里的事都好。秋后老母猪生下9只崽。今年价好，涨到7块，有卖头儿。卖猪崽的钱还清了去年的债。 
“上个月，那只黑老毋鸡被隔壁伢子打断了腿，我心疼了好几天，找到村上张兽医，他说不碍事。现在果真好了，只是有点跛。” 延叔腮帮子一鼓：“说这些干啥？菊，天冷了，叫你哥要当心自己，免得你娘挂念。告诉他家里人身体都好。”菊娘赶紧插上：“我就是晚上困不着，胃老是痛。叫你哥在学校吃饱吃好，想吃啥就吃啥。不要让人笑话咱。”菊烦透了：“哥是大学生，这点事都不懂？”
延叔把酒沥下，不够一盅，只好慢慢喝，边咂嘴边说：“菊，把你的学习情况给你哥说说。” 菊咬起下唇，写道：“上次期中考试我第一名，得了一张奖状和一枝钢笔。娘还蒸了鸡蛋给我吃。那枝笔很漂亮，我舍不得用，收在枕头底下……大学里也发奖状吗？你也要好好学习，争取得到奖状，让全家都高兴高兴。”
菊写好抬起头。延叔收回盯着菊飞快移动的小手的目光，倒放起酒盅。菊娘就站起去灶间盛饭。延叔又想起来什么，叫菊接着写：“前两天，上面分来救灾衣服。队长说你有出息，特地分给我家一件半新的呢子大衣， 让你回家过年穿。腊狗说样式还挺流行，城里都作兴。你不回家我就托人寄去。” 菊娘端出饭，也突然想起什么，叫菊再加上几句：“娘初一到后山庙里替你求了签，签上说你有小灾损，要切切注意。” 
菊嚷嚷起来：“没纸写了。”延叔见写了密密麻麻的三大张，说：“就不写了。”菊娘便说：“对。你哥不信这些。再说，写多了他没时间看，他的信就那么短。” 延叔端起饭碗扒拉了几口，又放下，仿佛心里有什么东西哽着。拿起那薄薄的一张纸，延叔瞪着眼前没了热气的几碟菜，硬邦郑地甩出一句：“重写一封。”正在有滋有味嚼饭锅巴的菊 愕然睁大眼睛，随即就按延叔的话庄重地写好第二封信：         
“信收到。钱就寄”。