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问题 填空题

下表为元素周期表中的一部分，列出10种元素在元素周期表中的位置，用化学符号回答下列各问题

（1）能形成共价键的元素有_______元素，共______种。

（2）只需形成一个共价单键就能达到稳定结构的元素有______。

（3）气态氢化物溶于水呈碱性的化合物是_______（填化学式）。

（4）10号元素最低正价含氧酸只具有________键。

（5）彼此间形成共价化合物数量最多的两种元素分别是_______ （填元素符号）。

（6）含氧量最高的离子化合物与共价化合物分别是________。

（7）①⑤⑦形成的化合物中，既含有_______ 键，又含有_______键，写出该化合物的化学式_______。

（8）某元素气态氢化物为H2B，最高价氧化物含B的质量分数为40%，气态氢化物的分子式为______，它与③结合形成的化合物的分子式为_________，含有的化学键有_________。

答案

（1）H，C，N，O，F，S，C1；7

（2）H，C1，F

（3）NH3

（4）共价

（5）C与H

（6）离子化合物Na2O2，共价化合物H2O2

（7）离子；共价；NaOH

（8）H2S；CS2；共价键

计算题

化简求值：4x2y﹣[6xy﹣2（4xy﹣2）﹣x2y]，其中x=﹣1，y=2．  
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阅读理解
阅读理解
A. When a child should learn to read
B. Why it is fun to teach a child reading
C. What if a child has reading problems
D. How you prepare a young child for reading
E. What is the best way to teach a child reading
F. Whether reading early promises later achievements
1. _____
Learning to read early has become one of those indicators - in parents' minds at least - that their child is
smart. In fact, reading early has very little to do with whether a child is successful academically. Research
has shown that difficulty with reading is often due not to inferior intelligence but to differences in the
developmental wiring of each individual child. In some cases, there are neurological problems and developmental lags that can be overcome with proper training.
2.
Traditionally, American schools teach children at age six, but many schools begin teaching informally in
kindergarten and pre-kindergarten. If parents start too early to encourage reading, and a child does not
immediately succeed, the parent has a hard time relaxing and letting the child go at his or her own pace.
3. _____
Over the years, research has proved that the use of both the "whole language" method and the "phonic"
method works best for a child to master reading. While the whole language approach, which includes
reading to children and getting them interested in both the activity of reading and the story they are
reading, is helpful, phonics must be taught. Children must be taught that one of the squiggles they see is
a "p" and another a "b". Getting the print off the page requires a different ability than being able to
understand the meaning of what is written.
4.  _____
You can start developing the skills needed in reading at a very young age without putting any pressure on
children. Besides reading to them, parents can start "ear training" their child by playing thyme games. This
develops the child's ability to recognize different sounds. In reading to children, parents also can point to
words as they go, teaching the child that the funny lines on the page are the words you are saying. All this
should be a fun activity.
5._____
Once a child is in school, the learning of reading is inevitably more serious. For children who have some
kind of reading difficulty, you must get a professional diagnosis. While the teacher might say the child is
merely disinterested but will get over it, disinterest or poor performance in reading can stem from a
number of things, some being very specific learning disabilities that can be identified and worked on. But it
is very tricky for parents to deal with their own child's learning disabilities.
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