题目

You  can't  imagine ________ when they received these nice Christmas presents.     A. how they were excited                B. how excited they were     C. how excited were they                D. they were how excited 答案：B 解析: how excited they were为宾语从句的语序。下列有关生态系统中的碳循环和人体体液中物质交换的示意图的描述中，正确的是　   甲　　　　　　　　乙A.乙图中的D是生态系统中的主要成分B.人体内氧气浓度最高的是甲图中的BC.人体发生过敏反应时，甲图中的A增加导致组织水肿D.在因捕食关系建立的食物链中，能量最少的是乙图中的B所处的营养级