题干

阅读理解。

    Holmes said, “Somebody sent a letter with five pips (桔核) in it from India, and arrived seven weeks later to kill John's uncle. Then they sent five pips from Scotland and arrived three days later to kill John's father. Now they have sent five pips to John from London!”

    “The letters are all from sea ports. The writer was on a ship when he wrote the letters,” I replied.

    “Very good, Watson! And John's enemy is in London already!”

    “Well, I hope they won't kill young John,” I said.

    But they did. The next morning, we read in the newspaper that a policeman found him die near Waterloo station. Holmes was very angry about it.

    “He came to me for help and those men murdered him! I'm going to find them, if it's the last thing I do!” he said to me, and he hurried out of the house.

    At night, when he came back, he was tired, but pleased, he said, “I know the names of John's enemies! And now I'm going to send them a surprise! This will frighten them!” He took five pips from an orange and put them in an envelope (信封). On it he wrote “S. H. for J. C.”

    “I'm sending the pips to captain James Calhoun. His ship is called the Star. He and his men are sailing back to Georgia, USA.”

    “How did you find him, Holmes?” I asked.

    “Ship's papers,” he said, “I've looked at hundreds of them today. Only one ship, the Star, was in the three ports at the right times, this morning the Star left London to sail back to Georgia. I found out that the captain and two of his men, all Americans, weren't on the ship last night, so I'm sure they killed John. When they arrive in America, they'll get the pips and then the police will catch them!”

上一题 下一题 0.0难度 选择题 更新时间:2017-03-15 07:54:07

答案(点此获取答案解析)

同类题3

过氧化钠(Na2O2)是一种淡黄色固体.某次科技活动中,某化学兴趣小组的同学将包有过氧化钠固体的棉花放入图2烧杯中,缓慢倒入二氧化碳后发现位于下面的蜡烛先熄灭,上面的蜡烛后熄灭,同时也惊奇地发现棉花燃烧起来.

(1)实验过程中蜡烛先后熄灭的现象说明了二氧化碳的一些化学性质.

(2)棉花为什么会燃烧呢?同学们联想起物质燃烧的相关知识,推理出棉花要燃烧,除了满足“棉花是可燃物”这一条件,还另需满足的条件是:____ .

提出问题:在实验中是如何给棉花燃烧提供条件的呢?

查阅资料:在常温下过氧化钠和二氧化碳能发生化学反应.

设计实验:经过讨论后,同学们设计了如下图的实验进行探究.

实验步骤:(1)按图1装配好装置,并检查其气密性;(2)把相关的试剂放入对应的仪器内;(3)推动注射器的活塞,把稀盐酸注入锥形瓶内,并固定活塞的位置;(4)一段时间后,在a处放置一根带火星的木条,观察现象.

实验现象:(1)干燥管中没有出现蓝色;(2)带火星的木条复燃;(3)饱和石灰水变浑浊.

实验分析:

(1)D装置的烧杯内变浑浊的原因是____ ;

(2)B装置中浓硫酸吸水干燥的作用,C装置的作用是____.

实验结论:

(1)“小木条复燃”说明过氧化钠和二氧化碳反应产生了____;

(2)“饱和的石灰水变浑浊”说明反应____ (填“吸收”或“放出”)热量,也使棉花满足了燃烧的条件.