A: 15
B: 15
C: 15
D: 10
The computer, help we human beings have stepped into the information age, should be regarded as one of the most important inventions in the 20th century.
12朵花,每____朵一份,分成了____份。12朵花,平均分成了____份,每份____朵。
世界上发达国家最为集中的地区是( )