如果一个随机变量X最多只能取可数的不同值，则为（  ）。

芸芸期末考试数学成绩不太好，只得了55分，但杨老师仍表扬了她，因为期中考试芸芸的数学只考了30分。杨老师所采用的评价方式属于（     ）

药物辅助治疗青少年牙周炎时宜选用的药物是（  ）

《英烈保护法》规定，每年(   )为烈士纪念日，国家在首都北京天安门广场人民英雄纪念碑前举行纪念仪式，缅怀英雄烈士。

关于面神经麻痹的叙述，哪项是错误的（  ）

幼小衔接不是只有在学前最后一年和小学一年级给予足够的重视，而应该在整个学前期都有意识地提高儿童的适应性。这说明幼小衔接应遵循的原则是(    )。

Passage1

When it comes to airline travel, perhaps nothing has revolutionized the passenger experience more than airline apps. Indeed, they' re becoming so ubiquitous that more than 50 percent of U.S travelers have at least one airline app installed on their smart device, according to travel industry research firm Phocuswright.

Maybe that's because apps make travel easier, and often are more functional than a kiosk or even an airline's own website. Passengers report that they' re often more quickly informed of a flight cancellation or gate change than an airline employee. Not all airline apps are created equal, but in general you can use an app to check in for a flight, change seats, and request and pay for an upgrade. Road warriors in particular appreciate mobile boarding passes and the ability to track their flights. Many airlines now offer free onboard streaming entertainment via apps. The Delta Air Lines app even allows users to track their bags, from check-in to carousel, while the Air France app lets passengers download magazines and newspapers from the airline's library 30 hours prior to departure.

But what if you are traveling extensively on more than one airline? Global airline alliances have their own apps that allow you to view flights for all member airlines and their affiliates, including code share flights. In general, you can find flight schedules for all member airlines and track member airline flights. Airport information is available, as are details about local weather at the destination. Where's the nearest airport lounge? The app will locate it for you.

The Sky Team airline alliance app goes a step further by letting its SkyPriority members (Sky Team Elite Plus members and customers with first and business-class tickets) find out exactly which SkyPriority services-including priority check in and baggage drop off, as well as access to priority security lanes and boarding lanes-are available at individual airports.

You' ll find that some alliance app features are available through multiple channels of communication. For example, Sky Team members have formed their own online community by sharing traveler tricks and airport tips accessible through a variety of channels, including the app, Sky Team's website, Facebook page and a dedicated tips site. Sky Team's YouTube page features travel tips from regional celebrities.

Just as airlines seem to have conquered social media, another method of communicating with travelers has just arrived. KLM Royal Dutch Airlines is the first carrier to sign up for Facebook's Messenger chat app. KLM flyers can automatically receive itineraries, flight updates, check-in notifications, boarding passes and rebook flights and communicate with customer service, all from Facebook Messenger. Messenger for Business was launched so that customers-in this case, passengers-can transact business over the messaging app in a single communication thread. Roughly 80 percent of passengers on planes traveling within the U.S. have the Messenger app installed on their smartphones, according to Facebook.

Clearly, mobile apps and social media have transformed our digital lives. Airlines favor apps and other technologies because they get customers out of airport lines and off phone lines. Through their smart devices, travelers now have untethered access to travel information. A few quick taps can supply individuals with information never dreamed possible even a decade ago. And with more people using smartphones as their primary computing device, and as more people own cellphones globally, people expect technology-driven methods of communication and convenience to accelerate. Whether you' re high-tech or not, you must admit that having immediate access to the information you need sure beats getting a busy signal on a toll-free phone line.

Which word below best describes the author's stance？

注射乙肝疫苗后产生的保护性抗体是

暑湿感冒，暑热偏盛，热盛烦渴者，治疗方剂宜首选（    ）

SARS病毒属于（    ）。