问题 单项选择题

图示结构,各杆线刚度i=常数,用力矩分配法计算时分配系数μA4为()。

A.

B.

C.

D.

答案

参考答案:C

解析:

A3杆的3支座与A2杆的2支座不同,3支座的约束作用相当于固定端,因此其转动刚度SA3=4i,而SA2=i,A1部分静定,转动刚度SA1=0,则

点评:本题考察的知识点为力矩分配系数的求解。掌握该类问题把握两个方面:一是熟练记住常见杆件约束的转动刚度,而是对于一些比较特殊的约束要从其对变形约束的实际情况出发来确定转动刚度,如题中的SA3

阅读理解

阅读理解。

     Just how comfortable is your sofa? Would you be prepared to let a stranger crash out there for the

night? And, on the basis of a bit of email correspondence and seeing a photo of the sofa belonging to

"An Unknown", would you travel halfway across the world to do the same? It might sound crazy, but

this is exactly what millions of people have done whilst participating in an activity known as couch

surfing.

     Couch surfing is travelling on a budget, using a broad network of contacts in order to get overnight

accommodation for free, or at as little cost as possible. Participants, also called couch surfers, join

dedicated websites, providing as much information about themselves as possible in order to make others

feel comfortable hosting them, or using them as a host. Various safety features are generally available in

such online networks, like verification (核实) of names and addresses,, personal references, and "vouching

(担保) for" a particular member; a reliable host or guest.

     As well as the financial advantages of couch surfing, participants also claim that the practice gives them

a more unique, authentic (真正的) travel experience, allowing them to experience culture and cuisine through

the locals, rather than from the confines of sanitized tourist accommodation. "We open our minds and lives

and welcome the knowledge that becomes available through cultural exchange." said Casey Fenton, founder

of Couch Surfing. com. "Couch Surfing wants to change not only the way we travel, but how we relate to

the work."

1. What is the right order of couch surfing?

    a. Provide personal information.

    b. Travel to the host's house.

    c. Join dedicated websites.

    d. Check photos of sofas by emails.

A. d-b-a-c

B. b-c-a-d

C. a-d-c-b

D. c-a-d-b

2. Which is NOT a safety feature of online network?

A. Verification of identity.

B. A copy of the passport.

C. Personal references.

D. Vouching for the member as reliable.

3. From the text we can know that _____.

A. participants can be hosted or a host

B. couch surfing tests people's patience

C. couch surfing leads to trust between people

D. people couch surf simply for financial reasons

4. What can be the best title of the test?

A. Touring the World on the Internet.

B. Unique Advantages of Local Travelling.

C. Around the World from Sofa to Sofa.

D. Cultural Exchange by Correspondence.

单项选择题