题目

George liked flying a plane. Once he bought a small plane and learned how to fly it. He soon became so good that he could make his plane do all kinds of tricks（技巧）. George had a friend. His name was Peter. One day George said to his friend, “ Peter, would you like to have a trip in my plane?” Peter thought, “ I’ve traveled in a big plane several times, but I’ve never been in a small one, so I’ll go.” They went up, and George flew around for half an hour and did all kinds of tricks in a shaken voice（颤抖的声音）, “ Well, George, thank you very much for thes一个三角形三边的长度分别是4分米、12分米、7分米，这个三角形的周长是23分米．　 　．