答案：That brush is his / hers. 解析：that 是those的单数,brush是brushes的单数,is 是 are 的单数,theirs的单数是his 或hers 翻译：那个毛笔是他/她的.希望能帮到你,祝更上一层楼O(∩_∩)O有不明白的请继续追问...