[解析]
11.A12.B
Double Ninth Festival is a special day for old people in China.The festival is on the ninth day of the ninth lunar month.This day,people show love for their grandparents.
People do many different kinds of things this day.They enjoy flowers,eat special cakes and drink wine.It's very interesting.The best way to celebrate it is to climb hills or mountains.People think that climbing will bring them good luck and help old people live long lives.