急性喉炎多由哪些病毒引起（） A.流感病毒 B.呼吸道合胞病毒 C.腺病毒 D.副流

肾损伤的手术指征不包括（）。

A.合并肠破裂

B.肾蒂损伤

C.肾挫伤

D.开放性肾损伤

E.肾盂破裂

香港、澳门回归后，已分别建立[ ]

A、特别行政区

B、经济特区

C、自治区

D、直辖市

发射高轨道卫星可以用如下方式进行：先把卫星送到近地圆轨道I，然后当卫星在I轨道上运行到P点时启动卫星自带火箭使卫星加速，卫星则变为在椭圆轨道II上运行，等卫星在轨道II上运行到Q点时再一次启动火箭使卫星加速，卫星变成在绕地圆轨道III 上运行．已知轨道I的半径为r，轨道III的半径为R，卫星在轨道I上运行的周期为T，则卫星在轨道II上从P点经半个周期到Q点的时间t=______．

Federal regulators Wednesday approved a plan to create a nationwide emergency alert（警报）system using text messages delivered to cell phones.

Text messages have exploded in popularity in recent years，particularly among young people.The wireless industry’s trade association, CTIA，estimates（估计）more than 48 billion text messages are sent each month.

The plan comes from the Warning Alert and Response Network Act，a 2006 federal law that requires improvement to the nation's emergency alert system.The act tasked the Federal Communications Commission (FCC) with coming up with new ways to alert the public about emergencies.

“The ability to deliver accurate and timely warnings.and alerts through cell phones and other mobile services is an important next step in our efforts to help ensure that the American public.has the information they need to take action to protect themselves and their families before, and during,disasters and other emergencies. ”FCC Chairman Kevin Martin said following approval of the plan.

Participation in the alert system by carriers—telecommunications companies is voluntary, but it has received solid support from the wireless industry.

The program would be optional for cell phone users. They also may not be charged for receiving alerts.

There would be three different types of messages，according to the rules.  

The first would be a national alert from the president，likely involving a terrorist attack or natural disaster.The second would involve “approaching threats，”which could include natural disasters like hurricanes or storms or even university shootings. The third would be reserved for child abduction（绑架）emergencies,or so-called Amber Alerts.

The service could be in place by 2010.

小题1: What is the purpose of the approved plan?

A．To warn people of emergencies via messages.

B．To popularize the use of cell phones.

C．To estimate the monthly number of messages.

D．To promote the wireless industry.小题2: The improvement to the present system is in the charge of ________.

A．CTIA

B．the Warning Alert and Response Network

C．FCC

D．federal regulators小题3: The carriers' participation in the system is determined by ________.

A．the US federal government

B．mobile phone users

C．the carriers themselves

D．the law of the United States小题4:. Which of the following is true of cell phone users?

A．They must accept the alert service.

B．They may enjoy the alert service for free.

C．They must send the alerts to others

D．They may choose the types of messages小题5:. Which of the following would be the best title for the text?

A，Cell Phone Alerts Protecting Students

B.   Cell Phone Alerts by Wireless Industry

C. Cell Phone Alefts of National Disasters

D. Cell Phone Alerts Coming Soon

高铁区间及站内两相邻线路中心线间的最小距离规定如下：曲线地段线路中心线间水平距离不加宽。