题目

Sam lives in a very tall building in a big city. There are twenty floors. He lives on the seventeenth floor. Every day he takes the lift to go up and down. Mike lives in the same building with him. He lives on the seventh floor. He usually walks to go up and down. Sometimes he takes the lift. He likes walking. He often says, “It does a lot of good to my body.”【1】Sam lives on the ________ floor. ( )A.7th B.17th C.20th【2】Mike lives on the ________ floor. ( )A.7th B.17th C.20th【3】Sam ________ walks to go up and down. ( )A.sometimes B.never C.every day【4】Sam and Mike live in a 关于ES细胞的叙述不正确的是A.形态上体积小、细胞核明显B.体外培养可以增殖而不分化C.ES细胞可以用来培育人造组织、器官D.ES细胞是指取自于原肠胚以后的细胞