The dog is playing with a ball.

狗正在玩球。

同一单元的其他句子

• Whose dog is this?这是谁的狗？
• This is my dog.这是我的狗。
• Is that your dog?那是你的狗吗？
• The dog is under the table.狗在桌子下面。
• Whose dog is that over there?那边是谁的狗？