YC6105QA型柴油机采用花辫型燃烧室，它是直接喷射式燃烧室中（）的变形。 A.U

后牙游离缺失的末端基牙上设计近中支托或采用应力中断式卡环的主要目的是（）

A．增强义齿的固位

B．增加义齿的强度

C．防止基牙龋坏

D．减轻牙槽嵴负担

E．减小基牙上的扭力

In the United States, the first day nursery was opened in 1854. Nurseries were established in various areas during the (91) half of the 19th century; most of (92) were charitable. Both in Europe and in the U. S. , the day-nursery movement received great (93) during the First World War, when (94) of manpower caused the industrial employment of unprecedented numbers of women. In some European countries nurseries were established (95) in munitions (军火)plants, under direct government sponsorship. (96) the number of nurseries in the U.S. also rose (97) , this rise was accomplished without government aid of any kind. During the years following the First World War, (98) , Federal, State, and local governments gradually began to exercise a measure of control (99) the day nurseries by (100) them and by inspecting and regulating the conditions within the nurseries.
The (101) of the Second World War was quickly followed by an increase in the number of day nurseries in almost all countries, as women were (102) called upon to replace men in the factories. On this (103) the U. S. government immediately came to the support of the nursery schools, (104) $6,000,000 in July, 1942, for a nursery school program for the children of working mothers. Many States and local communities (105) this Federal aid. By the end of the war, in August, 1945, more than 100,000 children were being cared (106) in day-care centers receiving Federal (107) Soon afterward, the Federal government (108) cut down its expenditures for this purpose and later (109) them, causing a sharp drop in the number of nursery schools in operation. However, the expectation that most employed mothers would leave their (110) at the end of the war was only partly fulfilled.

A．circumstance

B．occasion

C．case

D．situation

为什么人们在享受自己创造的财富的过程中，会时时受到大自然的种种惩罚因为在土壤侵蚀、沙漠化、滥伐森林、越来越多的物种灭绝、环境污染等所导致的生态系统的退化中，已经进步到能登月球、造核武器的人类，还没有真正揭开人与生物圈之间的秘密。 该段中“秘密”一词指的是( )。

A．人类为什么会受到大自然的惩罚

B．人类创造了财富还会受到惩罚的原因

C．人类应怎样在维持生态平衡的同时获得发展

D．人类怎样搞经济建设才能与环境相适应

如果当事人在施工合同中约定有仲裁条款，当合同其他条款无效时，应当认为( )。

A．仲裁条款有效，由仲裁委员会解决争议

B．仲裁条款有效，由人民法院解决争议

C．仲裁条款无效，由人民法院解决争议

D．仲裁条款无效，由双方另行选择争议解决方式

关于网桥和交换机，下面描述中正确的是（）。

A.网桥端口数少，因而比交换机转发更快

B.网桥转发广播帧，而交换机不转发广播帧

C.交换机是一种多端口网桥

D.交换机端口多，因而扩大了冲突域的大小