We asked, what is the percentage of the world's one-year-old children who have got those basic vaccines against measles and other things that we have had for many years: 20, 50 or 80 percent?
问 世界上有多少比例的一岁儿童 接种了那些我们已经使用了多年的 对抗麻疹以及其他疾病的 疫苗 百分之20 50 还是80?