题目

下列变化属于化学变化的是A．蜡烛受热融化B．瓦斯爆炸 C．自行车轮胎爆炸D．空气制氧气 答案：B解析:A、蜡烛熔化的过程中只是状态发生改变，没有新物质生成，属于物理变化．B、瓦斯爆炸生成水、二氧化碳等物质，属于化学变化C、轮胎爆炸没有新物质生成，，属于物理变化．D、用空气制取氧气的过程中没有新物质生成，属于物理变化．故选B． 阅读理解 　　On the morning of November 18, 1755, an earthquake shook Boston, Massachusetts．John Winthrop, a professor at Harvard College, felt the quake and awoke．“I rose, ”Winthrop wrote, “and lighting a candle, looked on my watch, and found it was 15 minutes after four, ”John Winthrop went downstairs to the grandfather clock．It had stopped four minutes before, at 4∶11．Except for stopping the clock, the quake had only thrown a key from the mantel(壁炉台)to the floor． 　　The clock had stopped because Winthrop had put some long glass tubes he was using for an experiment into the case for care．The quake had knocked the tubes over and blocked the pendulum(钟摆)．Winthrop, therefore, had the exact time that the earthquake had hit Boston．He looked at the key on the floor．The quake had thrown it forward in the direction of the quake's motion(运动)by a shock coming from the northwest, perhaps in Canada． (1) The text proves that ________． [　　] A． the power of nature is terrible B． earthquakes happen most often during nighttime hours C． the direction of an earthquake can be discovered D． universities study the cause of earthquakes (2) The earthquake happened ________． [　　] A． several minutes before the professor awoke B． and the professor awoke at 4∶15 C． in the centre of Boston D． when John Winthrop felt it (3) Choose the right order according to the text． a．The bed was shaking and John Winthrop awoke． b．John Winthrop looked attentively at his watch． c．John Winthrop got up to light a candle． d．The earthquake happened in Boston in 1755． e．John Winthrop knew the quake's direction． f．John Winthrop knew the exact quake's time． g．John Winthrop looked at the key on the floor． [　　] A． g, d, e, a, c, b, f B． d, a, c, b, f, g, e C． a, e, d, c, b, f, g D． e, d, g, b, c, a, f