查表可知,天然气的热值为煤气热值的2倍,这表明( ) A.产生相同的热量,使用

题型:选择题

问题:

查表可知,天然气的热值为煤气热值的2倍,这表明(   )

A.产生相同的热量,使用天然气的成本为使用煤气成本的2倍

B.产生相同的热量,完全燃烧天然气的质量为完全燃烧煤气质量的2倍

C.产生相同的热量,完全燃烧天然气的质量为完全燃烧煤气质量的1/2

D.天然气火焰的温度为煤气火焰温度的2倍

考点:热值热量的计算
题型:选择题

车削分度圆直径d1为60mm,轴向模数m为3mm的3头蜗杆。如果用分度盘分头法分头时,分度盘应转过几度?

题型:选择题

女性,46岁。有隆乳史,无意中发现左乳包块。查体:左乳外上象限可扪及一2cm×3cm包块,质硬,边界欠清,尚可推动。超声检查:肿块形态不规则,边缘呈分叶状,未见明显包膜。彩色多普勒超声显示肿块内血流分布杂乱,可探及高阻力动脉血流信号。

乳腺良性与恶性肿瘤的超声检查鉴别要点是().

A.边界是否光滑、完整

B.内部是否有钙化灶

C.后方是否有回声衰减

D.肿块纵径与横径比值>1,支持恶性肿瘤诊断

E.以上都是

题型:选择题

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.sources

B.abundance

C.shortage

D.reduction

题型:选择题

分子生物学检测在器官移植中的应用不包括()。

A.组织抗原配型

B.快速检测免疫抑制患者中所发生的感染

C.检测器官的功能

D.确认自体骨髓移植前肿瘤的有效净化

E.报告疾病的复发

题型:选择题

硬盘的一个主要性能指标是容量,硬盘容量的计算公式为

A.磁头数×柱面数×扇区数×512字节

B.磁头数×柱面数×扇区数×128字节

C.磁头数×柱面数×扇区数×80×512字节

D.磁头数×柱面数×扇区数×15×128字节

更多题库