Many people like animals．Now a lot of people keep animals as pets(宠物)．Usually people like to keep dogs，cats，fish and other animals．Many young people keep animals because they think these animals are interesting．Some old people keep pets because they don’t live with their children．

    Martin lives in No．25 Garden Street．He is a doctor(医生)，but he helps dogs．People usually call him The Dog Doctor．When their dogs get sick(生病)，they call him on the telephone．He goes to the people’s houses and helps them．He gives the dogs the right medicine(药物)．Wherever(无论)he goes，he is always welcome．

I think it's necessary         everyone to read a lot.    

有关岩石圈的说法，正确的是（　　）