题目

 Lingling and Betty ________ like _______ on the playground. A. doesn’t, run                B. don’t, run         C. don't, running       D.doesn’t , running 答案： B能使骨不断长粗，又能在骨折之后修复的结构是（　　）A.骨膜B.骨密质C.骨松质D.骨髓