完形填空
Zigfried, a little mouse, blew his breath on the frosty window of the farmhouse and rubbed it to see the outside. Still nobody came. Maybe today, he thought 1. It was only a few days before Christmas and he was watching for a miracle (奇迹).
This farmhouse had been 2 too long. It needed a family. Zigfried's 3 made a noise. He realized that he hadn't eaten anything since yesterday. He jumped from the windowsill (窗沿), grabbed a 4 from his home, and went next door to Farmer Mike's.
Farmer Mike's house had been a great place for the little mouse 5 the farmer married a wife who had a cat. Zigfried 6 when he thought of it. He looked around cautiously as he 7 into the room where grain was stored and was quite 8 as he filled his bag with wheat. He was turning to leave when suddenly he 9 a hot breath about his ear. His heart beat 10 , and without thinking he started to run and luckily 11 the cat's paws (爪子).
The next afternoon Zigfried heard some good news: a 12 family would be moving into the farmhouse soon. Zigfried's granny would arrive on Christmas Eve to 13 with him. He hoped that the family would come before his granny came. Before long, a car came 14 the road leading to the house, with butter sandwiches, cheese and chocolate.
Zigfried's Christmas miracle did arrive!
The house came 15 the next few days. Zigfried 16 every single hour of them. 17, the day before Christmas when he was drinking hot chocolate with a 18 smile at the door of his home, he heard the 19of the children of the family about what they might get for Christmas. What? A cat? The 20 froze on his face； his mouth fell wide open. After a long while, he at last found his voice: “Hey! Whose Christmas miracle is this?”
,则这个三角形一定是（ ）