问题 问答题 简答题

试述激光加工的基本原理及其主要应用场合(典型工艺)

答案

参考答案:

由激光发生器发射出的激光束通过透镜将激光束聚焦成极小光斑(直径几-十几um),其功率密度极高(108-1010W/cm 2);光能被工件吸收后便迅速转化为热能(光斑区温度可达1万℃以上),并致使材料熔化甚至气化,这种加工方法即为激光加工。激光加工的应用场合:打孔、切割、激光焊接、激光打标、激光热处理、激光雕刻、激光铣削、激光快速成形技术等。

阅读理解

Babies understand what their mothers say, even when they speak a language their children have never heard before, scientists claim.

The researchers found that one-year-olds reacted in exactly same way to their mothers’ voices regardless of whether they were speaking English or Greek, showing what mothers have long known – that babies pick up on tone of voice rather than the words themselves.

The researchers, from Cardiff University’s School of Psychology, observed babies as they watched their mothers perform actions with toys using the English words “whoops” and “there”. The scientists studied reactions from one-year-old babies to their mums’ voices even when they were speaking both English and Greek, and keeping the same tone of voice. The academics found that babies reproduced the same reactions regardless of whether they knew the language.  

Study leader Dr Merideth Gattis of Cardiff University’s School of Psychology says, “What this work showed was that children could have access to understanding simply through tone of voice. We did ‘whoops’ and ‘there’ in two languages and got exactly the same results.” The research, published in the journal Cognitive Development, was conducted on 84 babies aged between 14 and 18 months, over the course of a year, with none of the babies having any previous exposure to Greek.

Dr Gattis says that children respond to tone clues in their parents’ voices from an early age.

She says, “Tone of voice is a really useful signal of what someone is thinking. We never have direct access to other people’s minds, except the signals in language that they give out.” She says the study shows that it is less important what parents say than how they say it.

Dr Gattis adds, “A child may ask if you like his / her drawing, for example. You might say yes, but if you don’t sound enthusiastic, the meaning may not get across.” Before children begin to speak, parents should use exaggerated tone when speaking to them.

小题1:According to the text, what have mothers long-known?

A.Babies have a better understanding of English.

B.Babies pick up on tone of voice.

C.Babies like their mothers’ performances.

D.Babies like drawing from an early age.小题2:Which of the following is TRUE, according to the study?

A.Tone of voice is the most useful sign of what someone is thinking.

B.After children begin to speak, tone becomes unimportant.

C.The babies acted the same way regardless of the language.

D.The research was conducted on 48 babies.小题3:According to the text, Dr. Gattis believes that _________.

A.we have no access to other people’s minds

B.babies can’t understand what “yes” means

C.parents should always sound enthusiastic

D.how a parent speaks is more important than what he or she says小题4:What’s the text mainly about?

A.The content of the journal Cognitive Development.

B.The famous works of Dr. Gattis.

C.Babies understanding their mothers through tone.

D.Babies having the potential to learn language well.小题5:The text can be classified as _________.

A.a report

B.an advertisement

C.a handbook

D.a guide

选择题