阅读理解
I had been in the city for some time and was coming home. I missed my boat and decided to travel on an old ship. I knew that it would not be a comfortable journey but I had no time to wait for another boat.
Hardly had we left the port when I saw the dog Gulliver, the captain's favourite dog, for the first time. What a big dog it was! I had never seen one that could frighten me so much!
On the third day the ship caught fire. Nobody tried to put it out. The ship began sinking and all the men rushed to the life-boats. I saw no chance of getting away in a boat. Suddenly I remembered there was a life-raft on the ship. I had no time to lose, so I immediately rushed towards the raft and pushed it overboard.
In jumping down onto the raft I hurt myself badly and was unconscious for some time. When I came to, I found there was no sign of a life-boat. Every man who had been on board the ship must have gone down with her. I was the only one who was saved.
The I saw Gulliver was coming fast towards the raft. He struggled a long time before he managed to get onto it. I wanted to push him back into the water but did not dare to move. The dog shook himself, went to the other end of the raft and lay down. I didn't dare to sleep that night. I must watch him. In the moonlight I could see his eyes were open. He was watching, too.
恒过定点P，则过点P的抛物线的标准方程是（ ）