正确答案: B

R1

题目：由厚度相同的平壁组成的三层平壁，若λ1>λ2>λ3，则热阻R1、R2、R3之间的关系为（ ）。

解析：B

查看原题 点击获取本科目所有试题

举一反三的答案和解析：

[单选题]A in B for C with D toward

with

[单选题]The estimates in Economic Outlook show that in rich countries

oil price changes have no significant impact on GDP.

[多选题]下列关于哲学特点的说法中正确的有（ ）

属于上层建筑

是世界观和方法论的统一

解析：哲学都是对具体科学的概括和总结，但是只有正确的哲学，才是科学理论体系。唯心主义、形而上学是哲学理论体系但并不是科学的理论体系。哲学的确随着阶级社会的产生而产生，但不会随着阶级社会的灭亡而灭亡，到了共产主义社会仍然有哲学。在阶级社会中，哲学都有阶级性，属于上层建筑。哲学既是关于世界观的学说，又是关于方法论的学说，是世界观和方法论的统一。因此，正确选项为CD。

[单选题]表达产物具有G蛋白功能的癌基因是

ras基因

解析：

33．答案：C

[考点] 癌基因的基本概念

[分析] ras癌基因族包括：H-ras、K-ras、 N-ras，他们有相似的结构，所编码的蛋白质都是P21，位于细胞质膜内面，P21与G蛋白功能类似，如能与GTP结合、有GTP酶活性，并参与cAMP水平的调节，所以应选C。

[单选题]She felt suitably humble just as she _______ when he had first taken a good look at her city self, hair waved and golden, nails red and pointed.

had

解析：选［A］。本题重点考查动词的时态。句子的主句用的是一般过去时(felt)，由when状语从句的时态(过去完成时)可以判断出as后面的从句的时态也应该用过去完成时，即had felt。为避免重复，felt可以省略。

[多选题]社会主义初级阶段是

我国现阶段最大的实际和我国现阶段最基本的国情

邓小平理论的立论基础

建设中国特色社会主义的首要问题

制定路线方针政策的根本依据

解析：[答案] ABCD

[单选题]

ringsB． cycles

解析：答案：A

[多选题]Text 3 In recent years, railroads have been combining with each other, mergingsintossuper systems, causing heightened concerns about monopoly. As recently as 1995,the top four railroads accounted for under 70 percent of the total ton-miles moved by rails. Next year, after a series of mergers is completed, just four railroads will control well over 90 percent of all the freight moved by major rail carriers.Supporters of the new super systems argue that these mergers will allow for substantial cost reductions and better coordinated service. Any threat of monopoly, they argue, is removed by fierce competition from trucks. But many shippers complain that for heavy bulk commodities traveling long distances, such as coal, chemicals, and grain, trucking is too costly and the railroads therefore have them by the throat.

C