These aren't your cards. They are ( )(they).用所给词的正确形式填空.

填 theirs 他们的（东西）
These aren't your cards.They are theirs.
这些不是你们的卡片.它们是他们的（卡片）
再问： ( )he at home last night?(be）正确形式填空
再答： 填 Was Was he at home last night? 昨晚他在家吗？