问题 填空题

  • A.条件(1)充分,但条件(2)不充分
  • B.条件(2)充分,但条件(1)不充分
  • C.条件(1)和条件(2)单独都不充分,但条件(1)和条件(2)联合起来充分
  • D.条件(1)充分,条件(2)也充分
  • E.条件(1)和条件(2)单独都不充分,条件(1)和条件(2)联合起来也不充分

在设定条件下,数列为等差数列.
(1) 已知数列{an}的前卵项和Sn=n2+n+1
(2) 已知数列{an

答案

参考答案:B

解析: 利用an和Sn的关系来分析.
对于条件(1),
[*]
由此可知该数列为3,4,6,8,…,从第2项起是一个等差数列,但整个数列不是等差数列,因此条件(1)不充分.
对于条件(2),
[*]
由于a1=2也是在an=2n中,所以整个数列的通项公式是an=2n,即该数列是a1=2,公差为2的等差数列,因此条件(2)充分.
故选B

阅读理解

任务型阕读:阅读下面的短文,然后根据要求完成短文后面的题目。

The New York City Marathon was started by a man named Fred Lebow. It began in 1970 as a small, unimportant race. Only 127 people ran, and just 55 0fthem finished. They ran around Central Park four times. Few people watched them run. However, over the years the marathon grew and became more popular.

Today people come from all over the world to run in the marathon. Runners must be at least 18 years old, but there is no age limit(限制). In fact, the oldest runner was an 89-year-old man. Recently, more than 27,000 people ran in the New York City Marathon. Large crowds cheered the runners and offered them cold drinks and encouragement.

The course(路线) of the marathon has changed, too. Instead of running around Central Park, the runners go through the five districts of New York City: Queens, Brooklyn, Manhattan, the Bronx, and Staten Island. The marathon begins at the base(基座)of the Verrazano Narrows Bridge in Staten Island. The runners go across the bridge into Brooklyn. Then they go up through Queens and into the Bronx. The marathon finishes in Central Park in Manhattan. The complete course is 26. 2 miles, and takes the best runners less than 3 hours.

Although it has changed since 1970, the New York City Marathon is always exciting. Through the years, many unusual events(事件) have happened during the marathon. For example, Pat Tuz and John Weilbaker got married a few minutes before the race. Then they ran the race with their party members. Some people run the whole marathon as a family.  Other people run the race backwards.

In the fall of 1992, Fred Lebow, the founder(创始人) ofthe New York City Marathon,  slowly ran his last race. He was very ill with cancer, but he did not want to stop running. In October 1994, Fred died.

However, the New York City, Marathon, and all its excitement, will continue for many years to come.

小题1:根据短文内容完成句子(每空限填一个单词)。

In the first paragraph,  it tells us____ started the New York Marathonand        it began.

小题2:根据短文内容完成句子(每空限填一个单词)。

A runner has to go through five          and across two____ over the river before he completes the whole course today.

小题3:Mike is 16 years old, can he take part in the New York City, Marathon? Why or why not?

                                                                        

小题4:把短文中画底线的句子译成汉语。

                                                    

小题5:What does the writer want us to know about the New York City Marathon from the passage?(不超过10个单词)

                                                   

问答题 简答题