下列计算正确的是（ ） A．a6÷a2=a3 B．（-2）-1=2 C．（-3x2）

下列微粒中，质子数与电子数相等的是

A．Na⁺

B．Cl^—

C．OH^—

D．N

The Harvard Student—led Walking Tour

Let a student show you Harvard···on a free walking tour．

We welcome our neighbours to stop by the Harvard University Events＆Information Centre,

located in the Holyoke Centre Arcade at 1350 Massachusetts Avenue in the heart of Harvard Square in Cambridge．

Let a student take you and your family, school，or organization on an engaging，hour-long free historical tour of the Harvard Campus. The tours leave from the Events＆Information Centre．Not only will you discover the location of fascinating exhibition and programmers on campus，you will also see Harvard’s rich sampling of American history and architecture from the Colonial period to the present.

Schedule of Tours

Tours leave the Events＆Information Centre at 10 a.m. and 2 p.m. Monday through Friday, and at 2 p.m. on Saturday through the academic year (February4 through May 2；September 23 through December 16).Summer tours(June 24 through August 15)are offered at 10 a.m.,11：15 a. m．，2p.m．，and 3：15 p.m. Monday through Saturday．Reser—vacations for special tours of 20 or more people may be made by calling the Events＆Information Centre at (617)495-1573 or emailing icenter@ camail Harvard, edu. Tours are suspended March23 through April2 for Spring Break．May3 through June23 for Spring intercession(祷告),and August16 through September 22 for Summer intercession．

NOTE：Prospective(未来的)students may take tours originating at the Harvard Admission Office, located at Byerly Hall on 8 Garden Street in Cambridge．From April through August，the Admissions staff conducts an information session at l0a.m. followed by an 11 a.m. tour．Monday through Friday On Saturdays．there is no information session but the 11 a．m．tour is still scheduled．Another session is held year-round at 2 p.m. with a 3 p.m. tour following. For more information on tours for prospective students，please call at(617)495-1551．

Harvard University Events＆Information Centre

Location：Holyoke Centre Arcade．1350 Massachusetts Avenue，Cambridge MA 02138

Phone：(617)495-1573

小题1:A person can join in a tour at ________on Saturday through the academic year．

A．10 a.m.

B．2 p.m.

C．11：15 a.m.

D．3：15 p.m.小题2:If you want to go for an information session, you can go on __________.

A．May 2

B．June 23

C．August 20

D．September 1小题3:A student who wants an information session may _________for more information．

A．call (617)495-1573

B．call (617)495-1551

C．email icenter@ camail. Harvard.edu.

D．go to the Events＆Information Centre小题4:The above ad．is mainly intended for________．

A．foreign visitors

B．freshmen

C．high school students

D．those living near Harvard University

女性，52岁。右上腹隐痛6月，1小时前提取重物后突发头晕、心慌，面色苍白，既往有乙肝病史和胃病史。查体：P110次/分，Bp75/50mmHg，腹胀，右上腹压痛。化验：Hb69g/L，WBC9.0×10⁹/L，N0.70，HBsAg（+）。

治疗措施应采取（）

A.输血、输液，同时准备手术治疗

B.禁食、胃肠减压

C.胃肠减压，胃管内给止血药

D.经皮经肝胆道穿刺引流

E.经内窥镜注射硬化剂

简述合同权力的效力？

损害到国家安全的信息系统可能定级为（）。

A.一级系统

B.二级系统

C.三级系统

D.四级系统

E.五级系统