题目

17.基因型为Bb的动物，在其精子形成过程中，基因B与B、b与b和B与b的分开分别发生在（  ） ①精原细胞形成初级精母细胞  ②初级精母细胞形成次级精母细胞  ③次级精母细胞形成精细胞  ④精细胞变形成为精子 A.①②③                        B.③③②                C.②②②                     D.②③④ Photographer Zhang Zhongzeng has taken a series of photos showing people's lives around 40 years ago in Beijing. Born in 1957, Zhang has witnessed (目睹) China's changes since the reform and opening-up period began in 1978.Playing with birdsDate: 1983Location: DeshengmenDuring the 1980s, there were many elderly men who loved playing with birds. In the early morning, you could always see them holding bird cages, walking in the park or hutongs, on the road or under a tree. The hobby of playing with birds became popular during the Tang Dynasty and reached its heyday during the Qianlong period of Qing Dynasty.Now there are fewer Beijingers with birds, as elderly citizens' lives get richer and hutongs disappear from the city.Carriages (马车) in the cityDate: 1989Location: HepingliIn the 1980s, the trolley bus (无轨电车) and bus ran across empty roads, while carriages carrying goods or vegetables kept pace. During that time, traffic in Beijing was quite smooth, and three—wheeled motor vehicles, walking tractors and auto trucks could make use of the streets. The most commonly seen transportation was the bicycles, with different brands (品牌), styles and functions.Sugar—coated haws on a stickDate: 1988Location: Qian men WatchtowerAmong well-known Beijing snacks, bingtanghulu (sugar - coated haws on a stick) is probably the most famous, a city trademark.For children living in the 1980s in Beijing, when there were no Me Donald's or KFC's. bingtanghulu was their favorite snack. Now, for them a bite of bingtanghulu brings reminiscence and nostalgia (怀旧).【1】Why do fewer and fewer elderly citizens in Beijing play with birds?A.Because there are fewer birdsB.Because they have richer lives.C.Because they hate birds.D.Because they are very busy.【2】What was the most popular transportation in 1989?A.Motor vehicles.B.Walking tractors.C.Autotrucks.D.Bicycles.【3】What does the underlined word "reminiscence" mean in English?A.Luck.B.Memories.C.Interest.D.Treasure.