水是生命之源，生产之要，生活之基。今年3月22日是第二十届“世界水日”。我们每一个人都应该要做到：“珍惜水、节约水、保护水”。请完成下列问题：

（1）饮用酸碱度过大或硬度过大的水都不利于人体健康，可用              来测定水的酸碱度。检验水是硬水还是软水，可用的物质是            。

（2）河水中含有许多杂质，可利用吸附、沉降、过滤、蒸馏等方法净化，其中净水程度最高的是             。

The first and most important agents of socialization are the people who care for infants. In the earliest months, messages from nurturers constitute the child’’s basic understanding of the world around it. This is the infant’’s first introduction to the language that shapes perception and elicits emotion.Another powerful source of information and socialization is the friendship of peers. Peers are equals that one can deal with on the same level as oneself, whereas parents are superiors. The heavy emotional overlay of family relationships makes some kinds of learning difficult.Much formal socialization is placed in the hands of professionals. Teachers from kindergarten on are specifically designated agents of socialization. Ideally, a teacher is one who has both knowledge and the skills to present it. During the course of teaching their subjects, classroom instructors provide role models and attempt to convey the excitement of learning itself.In earlier times, parents, friends and teachers would comprise the list of primary childhood socializers. Children’’s books, comics and magazines might also have been mentioned as sources of information on norms and role models. Today one must add three powerful indirect or non-personal socialization agents: radio, movies and television. Many people learn about politics, form a vision of well-being, and develop attitudes towards others from what they see on the screen and hear through the speakers.

________ are the first formal socialization agents.

A．Infant nurturers

B．Family members

C．Group peers

D．School teachers