题干

已知曲线y=x+lnx在点(1,1)处的切线与曲线y=ax2+(a+2)x+1相切,则a= ____ 。

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同类题1

根据短文内容,从短文后的七个选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    The holiday season isn't about shopping and gifts.____ However, holiday travel can be more expensive than gifts. Fortunately, the following tips will help keep your travel spending under control.

    Plan ahead. The earlier you book your travel, from airfare to hotels, the easier it is to find good deals.____ Your best prices on airfare come when you book three weeks before the plane leaves for domestic(国内的) flights. For international flights, consider booking 30 days in advance. Many experts point out that you should book travel between one month and three months out for high-traffic holidays.

    Book your air travel on cheaper days. Traveling by air on Tuesdays and Wednesdays often costs less than on Fridays and Sundays. During the holidays, it's not just about a specific day of the week. You also need to consider the days surrounding the holiday but days immediately before and after a holiday can be expensive. One of the best ways to save is to plan your air travel on the day of the holiday.____

    Consider traveling overnight. Red-eye flights and overnight flights often cost less than those at more convenient times.____  Traveling overnight can help you avoid a night in the hotel, as well as save your money on travel to your destination.

    ____ You can't bring liquids with you on the airline, but you can bring sandwiches and other snacks. When you're on the road, you can buy food at local groceries to make your own meals, especially if you have access to(可使用) a microwave.

A. Bring your own food.

B. Consider affordable accommodations.

C. Traveling by plane is not the best choice.

D. Plus, booking earlier can save your money.

E. For instance, traveling on Christmas Day might be a great deal.

F. A great deal of travel also takes place during this time of year.

G. Other choices include sleeper trains as well as overnight ferries.

同类题5

阅读张伟的《移动支付新方式》一文,完成下列小题。

      ①互联网时代,效率要求被无限提高,安全更是不可忽视的需求,尤其是在网络支付方面。现在,在线支付和移动支付逐渐被越来越多的消费者所接受,现有的保障手段已经远远不够。因此,掌握和引领未来网络支付潮流的互联网巨头们,把目光转向了新的保障手段,比如指纹支付、ABCD等。与传统的输入密码相比,新的支付方式操作更方便,安全性也更高。

      ②对于指纹的应用,古老而新鲜:一方面,摁指纹在中国很早就被用作许可、同意、授权的凭证;另一方面,指纹解锁已经被广泛应用于智能手机的身份识别,苹果公司之前用iPhone5s手机引领了这一酷炫的设计。此外,在移动支付方面,继支付宝钱包、京东钱包启用指纹支付之后,近日,微信6.2版本也推出了指纹支付功能。用户在微信中开通指纹支付功能,下单后进入支付流程,根据界面提示将手指置于手机指纹识别区,仅用几秒便可完成支付。据介绍,微信指纹支付支持iOS8.0以上系统使用,安卓系统现仅华为mate7手机支持使用,后续将陆续支持其他机型手机。

      ③相比指纹,掌纹识别的应用是近些年才提出的概念。掌纹的形态由遗传基因控制,即使由于某种原因表皮剥落,新生的掌纹纹线仍保持着原来的结构。每个人的掌纹纹线都不一样,即使是孪生同胞,他们的掌纹也只是比较相似,而不会完全一样。因此,从理论上看,掌纹识别比指纹识别安全性更高,也越来越受到重视。

      ④2014年4月,瑞典隆德大学研究生弗雷德里克•雷夫兰德把掌纹支付变成了现实。他开发的掌纹支付技术无需智能手机、NFC芯片和应用程序便能实现支付。用户需先输入手机号码的最后4位,然后将手放在扫描仪上,接着就会从用户的银行账户扣除相应的金额。目前,他创立的公司已在当地的咖啡店和商铺中成功安装掌纹识别付款系统。

      ⑤除了指纹、掌纹,每个人的虹膜也是独一无二的。虹膜是位于眼睛黑色瞳孔和白色巩膜之间的圆环状部分,由相当复杂的纤维组织构成,包含很多相互交错的类似于斑点、细丝、条纹、隐窝等细节特征,这些特征在人出生前就以随机组合的方式确定下来了,一旦形成终生不变。虹膜识别的准确性是各种生物识别技术中最高的,所以使用虹膜识别技术进行授权在安全性方面无疑更具优势。

      ⑥2015年5月,富士通推出了全球首款搭载虹膜识别技术的智能手机Arrows NX F-04G。这款智能手机所搭载的虹膜识别技术通过凝视屏幕即可自动解锁,或是进行手机支付以及登录网页。

      ⑦相比以上技术,声纹识别也具有特殊的优势。首先,声纹特征的获取比较方便、自然,语音的识别成本也很低廉;其次,声纹识别使用简单,除了麦克风无需额外的录音设备,声纹辨认和确认的算法复杂度低,配合一些其他措施,如通过语音识别进行内容鉴别等,声纹识别的准确率可提升到极高程度。据悉,百度钱包正在研发声纹识别技术,用户在购物后,即可用声纹验证的方式取代传统密码完成支付。

      ⑧前段时间,在德国汉诺威消费电子、信息及通信博览会上,马云当着德国总理默克尔的面在网站上购买了一枚纪念邮票,令人吃惊的是,他竟然用自己的脸付了账。面部识别技术因此瞬间爆红,让人感觉“刷脸”的时代即将来临。