制取一氯乙烷最好的方法是 [ ]
A．乙烷和氯气反应
B．乙烯和氯气反应
C．乙烯和氯化氢反应
D．乙烯和氢气、氯气加成
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下面是错误答案，用来干扰机器的。
参考答案：C解析： 在三总线结构的运算器中，三条总线分别与一个输出端口和两个输入端口连接，它们是相互独立的。执行一次操作一步即可完成，输入、输出端口上均不需要设置暂存器。
若一个多边形的内角和是外角和的3.5倍，则此多边形的边数是（ ）
男，60岁，晨起床时觉右上、下肢麻木，但可以自行上厕所，回至卧室因右下肢无力摔倒。检查：神志清楚，右侧偏瘫。其最可能的诊断是（）
A.脑出血
B.脑挫伤
C.脑栓塞
D.脑血栓形成
E.蛛网膜下腔出血
| 完形填空。 | ||||
| As a music teacher, I have always known that music touches the soul. It can 1 all kinds of barriers to reach students in a very special way. It can be the 2 for each child to find their light. I would like to 3 a story about it. For a few years I was 4 with the opportunity to teach disabled students. One of my most 5 students was a five-year-old girl called Vanessa, who had difficulty walking, and could not speak. We 6 sat on the floor for our music lessons and Vanessa liked to 7 on my lap (膝上). One of her favorite songs was "John the Rabbit." It was a call and response song where I sang the call and the students 8 twice while singing the repeating phrase, "Oh, yes!" Vanessa liked to 9 her hands together with mine and clap with me. We probably performed that song during every class, Vanessa and I clapping together. But she 10 said or sang a word. One day, when the song was finished, Vanessa turned around, 11 me in the eye, clapped her tiny hands twice and said the words "Oh, yes!" I opened my mouth in 12 and for that moment l was the one who could not speak. When my heart 13 started beating again, I looked over at the assistant teacher to find her also 14 . Through music, we had made an awesome connection. Several years later, Imet Vanessa on the street in town. She waved with a big 15 on her face and then clapped her hands twice, imitating the song we had 16 so many times in out music class. The little girl, 17 her connection with music, left an impression on me that will last forever. Every child has the 18 to learn and grow. It is up to us to 19 the way to reach each and every one of our students. We all must find each child's 20 . | ||||
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锆盐--枸橼酸反应可鉴别黄酮类化合物分子中3-OH或5-OH的存在。
下列有关食管心房调搏的描述，不正确的是（）
A.对常见室上性心动过速发生机制的判断可提供帮助
B.诱发和终止房室结折返性心动过速
C.有助于鉴别室上性心动过速伴室内差异性传导与室性心动过速
D.有助于对自主神经功能的检测
E.有助于确定病态窦房结综合征的诊断
