题目

分子、原子和离子都是构成物质的粒子。请各举一例。 由分子构成的物质，如   (               )       。由原子构成的物质，如    (             )             。由离子构成的物质，如   (               )       答案：水  铁   氯化钠（正确即可）The villagers are extremely thankful to Mr. Jason, without whose help the road to the village_________.A.can't be builtB.couldn't have been builtC.mustn't be builtD.mustn't have been built