医院感染暴发是指在某医疗机构或其科室的病人中短时间内（） A.发生2例以上同种感染病

目前对于ABO基因学说较能被接受的是（）

A.单基因

B.等位基因学说

C.复等位基因学说

D.三等位基因学说

E.四等位基因学说

维也纳古典乐派的代表之一（）的音乐具有明朗、欢快的情调，其富有成果的领域是交响曲、室内乐和清唱剧，代表作有：《伦敦交响曲》，清唱剧《创世纪》。

A.沃尔夫冈•阿玛德乌斯•莫扎特

B.弗朗茨•约瑟夫•海顿

C.路德维希•凡•贝多芬

D.弗朗茨•舒伯特

下列各项中属于商业银行一级准备的是（）。

A.国债

B.同业拆借

C.商业票据

D.同业存款

Home prices slid in November, raising questions about whether the housing recovery is robust enough to maintain a sustained turnaround. From October to November, home prices fell 0.2% after (1) 0.1% in October, according to a report Tuesday by Standard & Poor’s/Case-Shiller’s home price index. (2) five of the 20 metro areas (3) by the index saw price increases for the month.

On a(n) (4) basis, prices were 5.3% lower in November than in November 2008. Prices were the same as in late 2003. "What we’ve seen (5) the past couple of months is that the pace of (6) has fallen down," says Maureen Maitland of Standard & Poor’s. "Some markets have (7) Is that because we haven’t (8) the foreclosure (回赎权的取消) cycle Because of unemployment We’re not seeing the (9) we were seeing in the last summer months. "

Metro areas that have seen a retreat in home prices (10) Seattle, Charlotte, Las Vegas and Tampa. All four (11) gains they made in recent months (12) . (13) , for the 20-metro index, the annual rate of decline is improving. That (14) , with other recent housing reports that show prices (15) or accelerating, could point to (16) the housing market is starting to (17) its footing, some economists say. Existing home sale prices were $178 300 in December, which is 1.5% higher than December 2008, according to a report this week by the National Association of Realtors. That was the first year-over-year (18) in median price since August 2007.

"The most (19) thing we can say is not only the market is stabilizing, but we’ve seen that housing demand is p," says Bernard Baumohl, with the Economic Outlook Group. "Housing probably will continue to climb upwards through the summer, (20) it could slip a little as the tax credit expires. \

15（）

A.fluctuating

B.stabilizing

C.declining

D.inclining

扭紧柴油机汽缸盖螺母时，没有按规定顺序和扭矩旋紧，或用力不均，扭矩不够或过大，使缸盖与缸体接合的密封性不好，在高温气流及水流的长期冲击下，漏气、漏水而烧损缸垫属于（）原因。

A.质量

B.安装

B.使用

D.压力