A:疫苗增强体内吞噬细胞对抗原的免疫记忆
B:疫苗多次强化刺激浆细胞产生大量的抗体
C:记忆细胞数量增多导致免疫效果显著增强
D:疫苗不断刺激效应 T 细胞分化成为记忆细胞
—I think teenagers should be allowed to make their own decisions when they have problems at school.
—_______. They're not calm enough, after all.