题目

在图中，小明与小刚用细棉线连接了两个纸杯，制成了一个“土电话”。 （1） 他们用“土电话”能实现l0m间的通话，这表明 。 （2） 相距同样远，讲话者以同样的响度讲话，如果改用细金属丝连接土电话，则听到的声音就大些。这一实验现象表明：。 （3） 如果在用土电话时，另一个同学用手捏住线上的某一部分，则听的一方就听不到声音了，这是由于。 （4） 如果在用土电话时，线没有拉直而处于松弛状态，则听的一方Sarah Williams went to a boarding school. Here is one of the letters she wrote to her parents from the school: Wentworth Girls’ school Beachside July 20th Dearest Mom and Dad, I’m afraid I have some very bad news for you. I have been very naughty and the school principal is very angry with me. She is going to write to you. You must come and take me away from here. She does not want me in the school any longer. The trouble started last night when I was smoking in bed. This is against the rules, of course. We are not supposed to smoke at all. As I was smoking, I heard footsteps coming towards the room. I did not want a teacher to catch me smoking, so I threw the cigarette away. Unfortunately, the cigarette fell into the waste-paper bas­ket, which caught fire. There was a curtain near the waste-paper basket which caught fire, too. Soon the whole room was burning. The principal phoned for the fire department. The school is a long way from the town and by the time the fire depart­ment arrived, the whole school was in flames. Many of the girls are in the hospital. The principal says that the fire was all my fault and you must pay for the damage. She will send you a bill for about a million dollars. I’m very sorry about this. Much love, Sarah P. S. None of the above is true, but I have failed my ex­ams. I just want you to know how bad things could have been! 1. Why did Sarah write home? A. To tell her parents about the fire. B. To ask for a lot of money. C. To tell her parents she had failed her exams. D. To tell her parents she had to leave school. 2. Why did Sarah tell her parents the story about the fire? A. She wanted to worry them. B. She wanted to make them laugh. C. She wanted to make them less angry at the real news. D. She wanted to warn them about what the principal was going to do. 3. The letter before the P. S. was ________. A. mostly true              B. partly true         C. all true                     D. completely untrue 4. Sarah said the principal was angry because ________. A. she had failed her exams                       B. it was her fault that had caused the fire C. she had not made the phone call in time   D. she had been caught smoking in bed