题目

Merry Christmas The winter holiday season is the most festive time of the year in the United States. Students from elementary school through college have about two weeks’ vacation, beginning shortly before Christmas and ending soon after New Year’s Day.    71    There are many parties to celebrate the birth of Christ and the arrival of the New Year.   72   Late in November, street lights and store windows are decorated with the traditional Christmas colors of red and green. Santa Claus, shepherd and angel scenes appear in shop windows. Winter scenes with snowmen, sleighs,如果a=3b，（a、b都是非零自然数）那么a和b的最小公倍数是（　　） A、aB、bC、ab