14.These are his sisters.(改为单数句) This is his sister. 15.This is my grandfather.This is my grandmother.(合并为一句) These are my grandparents . Ⅰ.补全对话 根据对话内容,从方框中选出能填入空白处的最佳选项。 A:Good morning,David. B:1. C Oh,Linda,that’s my family. A:2. E B...