完形填空
It was on such a cold morning, near Oxford Maryland. 1 I looked out of the window, I found the night’s snow had painted a completely white world. Suddenly a large Canada goose came into my sight. It was standing very still with 2 wings folded to its sides. Its feet were frozen to the ice of the river and it couldn’t move.
Then from the dark sky, I saw a line of swans moving freely. When they noticed the goose, they landed on the ice as 3 as possible. As the 4 came close to the goose, I was
5 that those great swan bills might hurt the goose’s body.
Amazingly instead, those bills began to 6 on the ice. It went on for 7 an hour. In the end, the goose was free. The swans rose again, and circled in the sky, waiting to see the 8 of their work.
However, the goose was still standing on the ice and 9 fly because of some ice held in its feathers. Then four of the swans watching in the sky came down to help it move the 10
away. Luckily, the goose was 11 and could move again.
When the goose spread its wings to their fullest, the four swans flew up into the sky and joined the circling group. They went on their journey to their secret land. Behind them, the goose was flying with joy. It 12 them and joined the last end of the line.
I 13them until they disappeared over the tips of the farthest trees. Only then did I realize that tears were running 14 my face. The swans were so warm-hearted that they 15the goose.
This is a true story. I always think of it in the bad moments, and tell myself, “If so for birds, why not for man?”
。已知
、
、
、
的质量分别为m1、m2、m3 、m4，真空中的光速为c。下列说法正确的是