A:甲向右侧弯曲生长
B:乙直立生长
C:丙向左侧弯曲生长
D:甲、乙、丙都弯向光源生长
下列选项符合抗体特点的是( )①是由淋巴细胞产生的 ②能与一定的抗原结合 ③能吞噬病菌 ④有些种类可长时间存留在人体内
请回答下列问题.
Kate is a new student. She is twelve. She is from America. She can speak English very well and she can speak a little Chinese. She is in Nanjing. Her parents are doctors. Kate is studying in a school near her home. She has some classes from Monday to Friday. On Saturdays and Sundays, she often plays games with her Chinese friends. She loves China and her Chinese friends.
①青少年应多吃一些含蛋白质丰富的食物,因为蛋白质是人体最主要的供能物质;
②某同学只吃肉类食品,不吃蔬菜和水果,结构牙龈经常出血,原因是缺乏维生素B;
③莉莉的妈妈一直给莉莉喂钙粉,可医生说莉莉患了佝偻病,原因在于喂钙粉时没加喂富含维生素A的食物;
④某些药物常被封装在淀粉制成的胶囊中服用,从消化道内的消化特点来看,原因是胃不能消化淀粉,胶囊可经胃进入小肠.