问题 选择题

由环己烷、乙醇、乙醚组成的混合物,经测定碳的质量分数为72%,则氧的质量分数为

A.19.6%

B.17.8%

C.16%

D.14.2%

答案

答案:D

三物质分别为C6H12、C2H5OH、C2H5OC2H5,可改变形式写为:C6H12、C2H4·H2O、C4H8·H2O,除H2O外,碳氢原子个数比均为1:2,碳氢质量比为6:1

当碳碳的质量分数为72%,对应的氢的质量分数为12%,则H2O所占的质量分数为16%,则氧元素的质量分数为16%×=14.2%

阅读理解

 Dear Sir or Madam,

Last Thursday, I traveled on the 8:00 a.m. train from Glasgow to London King’s Cross and I was quite angry about the service of your station.

The train didn’t come on time and it was forty minutes late when it left Glasgow. A man at the station said sorry to us, but he didn’t give us any reasons for the delay (误点). We then had further delays on the way and had to wait another thirty minutes. So I missed my plane from London to Frankfurt and had to wait for several hours.

What’s more (更重要的是), the service on the train was quite poor. The trip took more than five hours. Unluckily, we could buy nothing but some soft drinks on the train. Worst of all, something was wrong with the air conditioning and it got hotter and hotter in the train. Before we arrived in King’s Cross, the temperature was over 40℃.

Because of your poor service, I think you should pay me compensation (赔偿).

I’m looking forward to hearing from you.

Yours, David Robertson

请根据短文内容从所给的选项中选出最佳选项。

小题1:When did the train leave Glasgow?

A. At 8:00 a.m.             B. At 8:40 a.m.      C. At 9:00 a.m. 

小题2:How did David go to Frankfurt from London?

A. By plane.               B. By bus.      C. By car.

小题3:How long did David stay on the train?

A. 40 minutes.            B. 30 minutes.    C. Over 5 hours.

小题4:What could David buy on the train?

A. Hot dogs.            B. Sandwiches.    C. Soft drinks.

小题5:Which of the following is NOT true? 

A. This is not a thank-you letter.

B. David was very pleased with the trip.

C. The service of the station was very poor.

单项选择题