对放大器的工作性能描述,以下四项中不正确的是()。 A.负反馈使放大倍数增大 B.负

题型:单项选择题

问题:

对放大器的工作性能描述,以下四项中不正确的是()。

A.负反馈使放大倍数增大

B.负反馈提高了放大倍数的稳定性

C.负反馈使非线性失真减小

D.负反馈对输入电阻和输出电阻产生影响

考点:矿井维修电工矿井维修电工(中级)矿井维修电工(中级)题库
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()是指只会产生损失而不会导致收益的可能性。其损失发生的具体时间、具体的损失规模无法确定。在现实生活中普遍存在,如个人面临的疾病风险、机动车辆所有者面临车辆碰撞的风险、财产所有者面临偷窃或者火灾的风险等。这些风险的发生一定会带来损失,但它们何时发生、损害后果究竟有多大却无法事先确定。

A.收益风险

B.人身风险

C.纯粹风险

D.投机风险

题型:单项选择题

空调系统的新风量确定原则为( )。

A.取保持室内正压风量、保证每人不小于人员所需最小新风景中的较大值确定

B.按补偿排风风量、保证每人不小于人员所需最小新风量中的较大值确定

C.按补偿排风风量、保持室内正压风量、保证每人不小于人员所需最小新风量中的最大值确定

D.按不小于人员所需最小新风量,以及补偿排风和保持室内正压所需风量两项中的较大值确定

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A How to Use a Painting Knife 使用画刀的方法
Painting with a knife is a bit like putting butter on bread and produces quite a (1) result to a brush. Painting knives are excellent for producing textured, impasto work and (2) areas of flat colour.
What’s the difference between a palette knife and a painting knife
A palette knife is a long, straight spatula that is used (3) mixing paints and scraping a palette clean. They’re made from metal, plastic, or wood and (4) either be completely straight or have a slightly bent handle. A painting knife has (5) large crank in the handle, which takes your hand away from the painting surface. They (6) in numerous shapes(for example pear-, diamond-, or trowel-shaped) and are used for painting (7) of a brush. The edge of the knife is blunt, so that it doesn’t cut the (8) .
·What shape of painting knife should I use
Different shaped painting knives produce different effects. For example, a short blade produces angular strokes (9)a long blade makes it easy to put down sweeps of colour.
·Why can’t I use a palette knife to paint with
You can. Painting (10) just have the advantage of coming in more angular shapes and with sharper points. And (11) larger crank in the handle means there’s less chance of rubbing your knuckles into wet (12) . If you’re unsure whether you’re going to enjoy painting with a knife, first buy a (13) , plastic palette knife and experiment a bit with this before upgrading to a wood-and-metal knife.
·How do I use painting knife
(14) the handle firmly so you’re got good control. Pick up some paint off your palette (15) the tip, as you’d pick up some butter with a knife. Use the side of the (16) to spread paint across your canvas, or press it onto the canvas, as you (17) spread butter across a slice of bread.It’ll seem strange at first as it’s quite (18) to using a brush. Using just the tip of the blade will produce small dots. (19) the edge of the knife down will produce fine lines. Pressing the blade flat down (20) the paint will produce ridges. Scrape back into the paint to reveal underlying layers (called sgraffito).

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配制一定物质的量浓度的NaCl溶液时,造成浓度偏低的原因可能是(  )

A.定容摇匀后,有少量溶液外流

B.定容时,俯视液面

C.称量时,在天平托盘上放上称量纸,将NaCl固体放在纸上称量

D.溶解NaCl的烧杯未洗涤

题型:单项选择题

为促进我国高新技术产业的发展,国家规定:凡出口退税率未达到征税标准的,经国家税务总局批准,可按征税率办理退税。这将意味着,我国软件产品将以不含税价格进入国际市场,据此回答下面2题。

我国对高新技术产品出口税收的有关政策表明()

A.税收是组织财政收入的基本形式

B.税收是国家实现经济监督的重要手段

C.税收是实现资源优化配置的重要手段

D.税收是调节经济的重要杠杆

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