题目

汽车轮胎表面制成凹凸的花纹形状，这是通过增加接触面    来增大摩擦，自行车刹车时，用力捏闸，因增大了闸皮与车轮闸的    ，而增大了它们之间的滑动摩擦力，而迅速改变了自行车的    。 答案：粗糙程度    压力   动运状态Mobile phone has become a problem for middle schools. Some middle schools in Australia have banned(禁止) students from carrying mobile phones during school hours. Mobil phone use among children has become a problem for the school this year. Several children have got mobile phones as Christmas gifts, teachers said mobile phone use is a distraction(娱乐) to students during school hours and it also gives teachers so much trouble in their classrooms. Teachers were also saying that sometimes students might use phone messages to cheat during exams.She said some schools had tried to ban mobile phones. Some parents felt unhappy because they couldn’t get in touch with(与…联系) their children.Many teachers said students should not have mobile phones at school, but if there was a good reason, they could leave their phones at school office. They also said there were many reasons why the students should not have mobile phones at school: they were easy to lose and were a distraction from studies.Many people say that they understand why parents would want their children to have phones, but they think schools should let the students know when they can use their mobile phones.1.Some middle schools in Australia have banned students from carrying mobile phones______A. because they are students B. when they are freeC. when they are at school D. because they are children2.We know from the passage that some children get mobile phones from____A. the makers and sellers B. the passers-by and strangersC. their parents and friends D. some mobile phones users3.What does the underlined word cheat mean in the passage?_____A. 聊天 B. 核对 C. 查询 D. 作弊4.The passage tells us that_____A. students shouldn’t have mobile phones at school except for some special reasonsB. it is impossible to ban students from using mobile phones at schoolC. some parents felt unhappy because they couldn’t use their phones at schoolD. parents should teach their children how to use mobile phones during school hours.