问题 解答题

从6名短跑运动员中选出4人参加4×100 m接力赛.试求满足下列条件的参赛方案各有多少种?

(1)甲不能跑第一棒和第四棒;

(2)甲不能跑第一棒,乙不能跑第四棒

答案

(1)240;(2)252;

题目分析:(1)可优先考虑特殊元素甲,此时务必注意甲是否参赛,因此需分两类,甲参赛和甲不参赛,利用分类加法计数原理求解

(2)显然第一、四棒为特殊位置,与之相伴的甲、乙则为特殊元素,这时特殊元素与特殊位置的个数相等,利用特殊位置(元素)优先考虑的原则解之.

(1)优先考虑特殊元素甲,让其选位置,此时务必注意甲是否参赛,因此需分两类:

第1类,甲不参赛有种排法;

第2类,甲参赛,因只有两个位置可供选择,故有A种排法;其余5人占3个位置有A种排法,故有AA种方案.所以有=240种参赛方案.

(2)优先考虑特殊位置.

第1类,乙跑第一棒有=60种排法;

第2类,乙不跑第一棒有=192种排法.

故共有60+192=252种参赛方案.

单项选择题 A3/A4型题
阅读理解

HANGZHOU-As a major province neighboring Shanghai, Zhejiang is set to benefit from the Expo in the city this year in more ways than one.

According to a survey from the Bureau of Shanghai World Expo Coordination, 80 percent of the respondents (回答者) going to the Expo have plans to travel and 75 percent of them will go to nearby places, such as Zhejiang and Jiangsu provinces. Hangzhou, Suzhou, Nanjing and Wuxi are the most popular sites, where tourism will be the best winner.

It is estimated (估计) that 70 million visitors will come to the Expo. During the peak time, as many as 700,000 people will visit Shanghai every day.

When all services such as hotels, meeting rooms, and transportation in Shanghai are full, it is possible for other activities to be held in nearby cities. And this is the golden opportunity for developing local tourism. The local hotel industry will benefit directly from the event.

Due to the Shanghai World Expo, Zhejiang will attract 20 million visitors within half a year. It will encourage local industries, such as catering, tourism, entertainment and shopping. More than 50 travel routines (线路) connecting Shanghai and other tourism spots, such as the West Lake in Hangzhou, gardens in Suzhou, and the waterscape in Shaoxing, will be introduced to the world. So far, local travel bureaus in Hangzhou, Ningbo, Huzhou, Shaoxing, Zhoushan, and Wenzhou have already sent special work teams to Shanghai to present their special tourism attractions to visitors.

The sharing and the connections of tourism resources as well as customer and service systems will also promote the areas in the Yangtze River Delta, which will in turn help to shape sustainable (可持续的), healthy tourism for the future.

64. What is the best title for the passage?

A. Hangzhou-the Heaven on earth

B. The Expo Shanghai 2010-a great success

C. Being at right place, right time for traveling

D. A good chance to develop tourism and others

65. Which of the following is TRUE according to the passage?

A. There will be more than 50 travel routines in Shanghai.

B. 75% of the people in Zhejiang will go to visit the Expo.

C. The local tourism will benefit a lot due to the Expo.

D. Hangzhou will benefit the most from the Expo.

66. What can be inferred from the passage?

A. More cities in neighboring provinces will be better known to the world.

B. Work teams have been sent to Shanghai to present the attractions to visitors.

C. As many as 700,000 people will visit Shanghai every day.

D. The Shanghai World Expo will promote all industries.

67. Which section of a newspaper may the article be taken from?

A. opinion        B. advertisement             C. news               D. sports