One day, a teacher was giving a speech to his students .He held up（举起）a glass of water and asked the class. How heavy do you think this glass of water is ?The students' answers ranged（范围
阅读理解。 Mr. and Mrs. Smith had always spent their summer holidays in New Jersey in the past, staying in a small inn (旅店) at the foot of a hill. One year, however, Mr. Smith made a lot of
折叠后，点
、
分别落在
、
处，若
，则
。
