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问题 单项选择题 B型题

急性化脓性骨髓炎的X线征象（）

A.项圈征

B.棕色瘤

C.砂粒状死骨

D.大块死骨

E.Schmorl结节

答案

参考答案：D

解析：骨结核在骨质破坏区内形成的死骨较小，呈砂粒状。急性化脓性骨髓炎死骨较大，呈大块死骨，甚至病骨大部骨干成为死骨。椎弓崩裂好发于第5腰椎，腰椎斜位片上，崩裂的椎弓峡部（"狗颈部"）可见一带状裂隙，宛如戴了一个项圈，称为项圈征。甲状旁腺功能亢进时破骨活动增强，引起骨吸收，骨吸收区可被纤维及肉芽组织替代，后两者可出现继发性黏液变性和出血，因富含含铁血黄素而呈棕红色，称为棕色瘤。

选择题

白钨矿（主要成分为CaWO4）是一种重要的含钨矿物，CaWO4中钨元素（W）的化合价是（　　）

A．+6

B．+4

C．+2

D．-2
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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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