题目

 Not until he left his home          to know how important the family was for him. A. did he begin         B. had he begun       C. he began             D. he has began 答案：A古诗词中有许多描述光现象的句子，如“潭清疑水浅”、“池水映月明”，这两句诗描述的分别是光的A.反射、反射B.折射、折射C.反射、折射D.折射、反射