问题 选择题

类推是一种重要的学习方法,但如果不具体问题具体分析就会得出错误结论。下列类推结论正确的是

A.SiH4的熔沸点比CH4高,则PH3的熔沸点比NH3

B.钠在空气中燃烧生成过氧化钠,则锂在空气中燃烧生成过氧化锂

C.Al(OH)3能溶于NaOH溶液,则Be(OH)2能溶于NaOH溶液

D.甲酸甲酯能发生银镜反应,则乙酸甲酯能发生银镜反应

答案

答案:C

题目分析:A、CH4和SiH4比较,相对分子质量越大,范德华力越大,故沸点高,而NH3和PH3比较前者分子间存在氢键沸点高,故A错误;B、钠和锂是同族元素,性质具有递变性,Na比Li要活泼更易失电子,故B错误;C、Be和Al是同族元素,性质具有递变性,都是两性氢氧化物,既能和强酸反应,又能和强碱反应,故C正确;D、银镜反应是醛基的特有反应,甲酸乙酯中,酯键中羰基碳上连着一个氢,可以看作是一个醛基,所以能发生银镜反应,而乙酸甲酯中,酯键中羰基所在碳上没有氢,就不具备醛基的性质。故D错误。

多项选择题
阅读理解

B

When I was looking at my railway timetable, I read with satisfaction that there was an express train (快车) to Westhaven. It went to the station in my hometown and the journey lasted only an hour and 17 minutes. When I got on the train, I couldn’t help noticing that a lot of villagers got on as well. At that time I was not surprised at all. I thought that there might be many people besides myself who wished to take the express train to save time. Neither was I surprised when the train stopped at Wildly, a small station a few miles along the line. Even an express train can be delayed sometimes. But when the train stopped station after station, I began to wonder. It suddenly struck me that this express was not running down the line at 90 miles an hour, but no more than 30. One hour and 17 minutes passed and we had not covered half the distance. I asked a passenger if this was Westhaven Express, but he said he had not even heard of it. Two hours later, I was talking angrily to the station master at Westhaven. When he said there was not such an express train, I asked for his copy of the timetable. There was a sign of victory in my voice when I told him that it was there in black and white. Looking at the timetable, he told me to look careful. At the bottom of the page it said, “This service has been stopped.”

61. The passage mainly tells us about ______.

A. the writer’s unhappy journey on a train

B. a mistake in the railway timetable

C. a careless mistake made by the writer

D. the reason why the train was delayed

62. An express train should travel at the speed of ______.

A. more than 40 miles an hour

B. no more than 40 miles an hour

C. 90 miles an hour

D. less than 90 miles an hour

63. Which of the following is true according to the story?

A. The writer got a wrong timetable.

B. The writer had wanted to take an express train.

C. The villagers got on an express train to save time.

D. None of the passengers had heard of Westhaven Express

64. The writer didn’t realize he was on the wrong train until ______.

A. he saw a lot of villagers getting on the train

B. the train stopped at a small station

C. he found the train was delayed

D. an hour passed after he got on the train

65. What was the writer’s mistake?

A. He didn’t notice the words at the bottom of the timetable.

B. He didn’t know that Westhaven Express was not in the timetable at all.

C. He got on a train which didn’t go to Westhaven.

D. The express train changed it speed.