题目

已知向量a=(1,2),b=(-3,2),且向量ka+b与lb+a平行，则实数k、l满足的关系式为 A.k·l=-1         B.k-l=0             C.l+k=0             D.k·l=1 答案：D 解析：ka+b=(k,2k)+(-3,2)=(k-3,2k+2)，lb+a=(-3l,2l)+(1,2)=(1-3l,2+2l)，∵平行,∴(k-3)(2+2l)-(2k+2)(1-3l)=0.整理得kl=1.  The 2007 Special Olympics(特奥会)World Summer Games ended in  Shanghai a week ago．This two-week sports meeting is full of love and caring(关爱)，because 40,000 volunteers(志愿者)(70％of them are college students )and more than 100,000 workers，family members in the city served for(为．服务)the people from more than 160 countries．     The Special Olympics gives hope to the people who have mental illness(智障)-10 million in China and 170 million all over the world．     Many of these volunteers spent their time during the National Day holiday  week traveling across the city，working 12-hours a day．China(with 1,200 members)gets more gold medals than any other country．But the most important for the Special Olympics is to join the games，a spirit of courage，sharing，skill and joy，not get metals This spirit will encourage mil lions of people to be strong in their lives．This spirit will also teach people to show  more respect and care to the people who have mental illness．     The Special Olympics have also provided people from Shanghai with a chance to show their new look．     The 2007 Special Olympics was a great Success．It is at least as important as the 2008 Beijing Olympics．                                  (China Daily 10/20/2007 page4) 1．---What of the above(A，B，C，D)is the 2007 Special Olympics Games’ symbol(会标)?    ---______________． 2．When did the 2007 Special Olympics World Summer Games end?   A．Oct．1，2007    B．Oct．27，2007    C．Oct．11，2007    D．Oct．20，2007 3．How many countries join the 2007 Special Olympics Games?   A．More than 160．  B．More than 170．    C．40,000．    D．120． 4．What is the most important for the Special Olympics?   A．To get more metals．    B．To break records．   C．The spirit of courage，sharing，skill and joy．    D．Both A and B．