问题 问答题 简答题

衍射仪测量在入射光束、试样形状、试样吸收以及衍射线记录等方面与德拜法有何不同?

答案

参考答案:

入射X射线的光束:都为单色的特征X射线,都有光栏调节光束。不同:衍射仪法:采用一定发散度的入射线,且聚焦半径随2θ变化,德拜法:通过进光管限制入射线的发散度。试样形状:衍射仪法为平板状,德拜法为细圆柱状。试样吸收:衍射仪法吸收时间短,德拜法吸收时间长,约为10~20h。记录方式:衍射仪法采用计数率仪作图,德拜法采用环带形底片成相,而且它们的强度(I)对(2θ)的分布(I-2θ曲线)也不同。

单项选择题

So long as teachers fail to distinguish(differ) between teaching and learning, they will continue to undertake to do for children that which only children can do for themselves. Teaching children to read is not passing reading on to them. It is certainly not endless hours spent in activities about reading. Douglas insists that "reading cannot be taught directly and schools should stop trying to do the impossible".

Teaching and learning are two entirely different processes. They differ in kind and function. The function of teaching is to create the conditions and the climate that will make it possible for children to plan cleverly the most efficient system for teaching themselves to read. Teaching is also a public activity. It can be seen and observed.

Learning to read involves all that each individual does to understand the world of printed language. Almost all of it is private, for learning is an occupation of the mind, and that process is not open to public scrutiny.

If teacher and learner roles are not interchangeable, what then can be done through teaching that will aid the child in the long search for knowledge Smith has one principle rule for all teaching instructions. "Make learning to read easy, which means making reading a meaningful, enjoyable and frequent experience for children. "

When the roles of teacher and learner are seen for what they are, and when both teacher and learner fulfill them properly, then much of the pressure and feeling of failure for both is got rid of. Learning to read is made easier when teachers create an environment where children are given the chance to solve the problem of learning to read by learning.

The main idea of the passage is that ().

A. reading is more complicated than believable

B. reading ability is something gained rather than taught

C. teachers should encourage students to read as widely as possible

D. teachers should do as little as possible in helping students learn to read

解答题