搜题请搜索小程序“爱下问搜题”
问题 填空题

从1，2，3，4，5，6，7，8中任取三个数，能组成等差数列的概率是______．

答案

一共8个数，从8个数中任取3个数共有

C38
=
8×7×6
3×2×1
=56种情况

三个数能组成等差数列，分为：

①公差绝对值为1的共有6种情况；

②公差绝对值为2的共有4种情况；

③公差绝对值为3的共有2种情况；

因此能组成等差数列的情况总数为12种情况

故能组成等差数列的概率是P=

12
56
=
3
14

故答案为：

3
14

单项选择题

随着我国房地产金融的不断创新和发展，以前不适合在房地产投资领域使用的（）形式越来越得到普遍应用。

A.长期投资、实物投资和直接投资

B.长期投资、间接投资和实物投资

C.短期投资、实物投资和金融投资

D.短期投资、间接投资和金融投资
查看答案
填空题


In the following passage, there are 20 blanks representing the words that are missing from the context. You are to put back in each of the blanks the missing word． The time for this section is 20 minutes.
Where do you really come from And how did you get (1) where you live today DNA studies suggest that all humans today (2) from a group of African ancestors who—about 60,000 years ago— (3) a remarkable journey.
The Genographic Project is seeking to chart new (4) about the migratory history of the human species by (5) sophisticated laboratory and computer analysis of DNA contributed by hundreds of (6) of people from around the world． In this unprecedented and real-time (7) effort, the Genographic Project is closing the gaps of what science (8) today about mankind’s ancient migration stories.
The Genographic Project is a five-year (9) partnership led by National Geographic Explorer-in-Residence Dr. Spencer Wells. Dr. (10) and a team of renowned international scientists and IBM researchers, are (11) cutting-edge genetic and computational technologies to analyze historical patterns in DNA (12) participants around the world to better understand our human genetic roots. (13) three components of the project are: to gather field research data (14) collaboration with indigenous and traditional peoples around the world; to invite (15) general public to join the project by purchasing a Genographic Project Public Participation Kit; (16) to use proceeds from Genographic Public Participation Kit sales to further (17) research and the Genographic Legacy Fund which in (18) supports indigenous conservation and revitalization projects. The Project is anonymous, non-medical, (19) , non-profit and non-commercial and all results will be placed in the (20) domain following scientific peer publication.

查看答案