一台三相感应电动机的额定电压UN=220V,定子三相绕组为△接法。启动时将定子绕组改

题型:单项选择题

问题:

一台三相感应电动机的额定电压UN=220V,定子三相绕组为△接法。启动时将定子绕组改为Y接法,并接在380V的交流电源上,则电机的启动电流与接在220V电源上仍为△接法直接启动时相比较,则Y接法的启动电流比△接法的启动电流()。

A.增大

B.减小

C.不变

D.不确定

考点:注册电气工程师电气工程专业基础电气工程基础(二)
题型:单项选择题

生物兴趣小组的同学在培养草履虫时发现,草履虫常集中在培养液的表层,原因是培养液的表层

A.氧气充足 

B.阳光充足

C.营养丰富 

D.温暖

题型:单项选择题

奈瑟菌属的共同特征:革兰阴性双球菌呈肾形或豆形,在临床标本中,多位于中性粒细胞内。专性需氧生长,初次分离培养时须供给5%CO2。营养要求高,需用巧克力琼脂培养基。最适生长温度为35~36℃,培养48h后,形成凸起、圆形、光滑、透明的小菌落。易产生自溶酶,人工培养物如不及时转种,细菌常自溶死亡。

关于两种奈瑟菌的鉴别,下列叙述正确是

A.脑膜炎奈瑟菌可分解麦芽糖,淋病奈瑟菌不能分解麦芽糖

B.脑膜炎奈瑟菌可分解葡萄糖,淋病奈瑟菌不能分解葡萄糖

C.脑膜炎奈瑟菌氧化酶阳性,淋病奈瑟菌氧化酶阴性

D.脑膜炎奈瑟菌氧化酶阴性,淋病奈瑟菌氧化酶阳性

E.脑膜炎奈瑟菌凝固酶阳性,淋病奈瑟菌凝固酶阴性

题型:单项选择题

 It should go without saying that the focus of UML is modeling. However, what that means,exactly, can be an open-ended question. (1) is a means to capture ideas, relationships,decisions, and requirements in a well-defined notation that can be applied to many different domains. Modeling not only means different things to different people, but also it can use different pieces of UML depending on what you are trying to convey. In general,a UML model is made up of one or more (2) .A diagram graphically represents things, and the relationships between these things. These (3)can be representations of real-world objects,pure software constructs, or a description of the behavior of some other objects. It is common for an individual thing to show up on multiple diagrams; each diagram represents a particular interest, or view, of the thing being modeled. UML 2.0 divides diagrams into two categories:structural diagrams and behavioral diagrams.(4) are used to capture the physical organization of the things in your system, i.e., how one object relates to another.(5) focus on the behavior of elements in a system. For example, you can use behavioral diagrams to capture requirements, operations, and internal state changes for elements.

空白(1)处应选择()

A.Programming

B.Analyzing

C.Designing

D.Modeling

题型:单项选择题

EDI是通过计算机通讯网络进行()的传递

A、商业文件

B、电子数据

C、标准格式数据

D、交易单证

题型:单项选择题

人民群众满意不满意、赞成不赞成、答应不答应,是衡量公安工作的最高标准。 ( )

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