After I finished my classes, I walked to home. Suddenly, I saw a dog run towards me.I was very frightening. I guessed that it would attack me, because I started to run before the dog reached to me. Soon, the dog caught up with me, but to my surprised, it ran past me as if it hadn’t seen me. I see some people running after a dog. I asked them the reason why they were chasing after the dog.They told that the dog had bitten his chicken the night before.

After I finished my classes, I walked to home. Suddenly, I saw a dog run towards me.I was very frightening. I guessed that it would attack me, because I started to run before the dog reached to me. Soon, the dog caught up with me, but to my surprised, it ran past me as if it hadn’t seen me. I see some people running after a dog. I asked them the reason why they were chasing after the dog.They told that the dog had bitten his chicken the night before.

I saw a dog ________ to a tree beside the gate.

1. A.
   tie
2. B.
   being tied
3. C.
   having tied
4. D.
   tied

I saw a dog ________ to a tree beside the gate.

[　　]

I saw a dog ________ to a tree beside the gate.

[　　]