阅读下面的短文，从短文后所给各项的四个选项(A、B、C、D)中选出能填入相应空白处的最佳选项。 People live in groups, which we call societies. Societies and social relations are the subjects ( 1) in the social sciences. Men depend on other men and on the world around ( 2). The sun brings them warmth (暖和，热烈) and light, day and night, summer and winter. Plants grow ( 3) there is air and sunshine, earth and water. animals depend on plants. ( 4) depend on water, air, sunshine, and the plants and animals around them. Wherever people live and ( 5) they look like, many of their requirements are the ( 6). They need food and places to live ( 7), warmth and sleep. They need ( 8) social existence (存在，生存), they need friendship and relationship (关系) which will ( 9) to marriage and family life. The members of a society depend on one ( 10). In different societies we find different ways of finding ( 11) and different methods of preparing it. Societies have ( 12) habits and customs. They teach their children, care for ( 13) people, look after old people in various ways. They have different ( 14) in life, death and the world ( 15) which they were born. Most men ( 16) to live in peace. The members of every social group accept certain rules and customs ( 17) expect other members to know them. Children are taught to ( 18) these rules, and what they do in ( 19) life depends partly on the habits they ( 20) when they were young. 1.explained learned searched studied 2.it them us everyone 3.that where whether for 4.men lives societies relations 5.however which how whatever 6.like similar one same 7.on in with by 8.of for a that 9.go move lead come 10.other another each thing 11.food meal crops minerals 12.old modern various limited 13.educated healthy sick middle-aged 14.talks positions beliefs attitudes 15.from over into beyond