This paper mainly discussed the important role of symmetrical principle on atom structure and chemical bond.

She said: " Our match is made in heaven, there is a chemical bond between us. "

她说: “ 我们是天作之合, 我们之间有化学反应. ”

A chemical change always results in forming at least on new substance.

一种化学变化总是产生至少一种新物质.

The chemical change off heat and light.

这种化学变化发出热和光.

New material can be brought about through chemical change.

通过变化可以生成新的物质.

Whenever a chemical change takes place, There is a new substance formed.

每当发生化学变化时, 就有一种新的物质生成.

When rust is formed, a chemical change has taken place.

当锈生成时, 就发生了化学变化.

We saw that a chemical change had taken place.

我们看到已发生了化学变化.

Heat and light can be given off by this chemical change.

这种化学反应能放出热和光.

A chemical change takes place in paper when it burns.

纸燃烧时就发生了化学变化.

Wherever a chemical change takes place , there is a new substance formed.

每当发生化学反应, 都会产生新物质.

The chemical change absorbing heat is named an end – thermal reaction.

吸收热量的化学反应被称为吸热反应.

A chemical change takes place in any substance when it burns.

物质燃烧时产生化学变化.

This chemical change can be expressed by an equation.

我们可用反应式表示这种化学变化.

The chemical change gives off [ out ] heat and light.

这类化学变化发出 热乎 光.

The chemical composition and casting technology of the lining were described also.

同时还介绍了该衬板的化学成分和铸造工艺.

Choice having introduced the hammerhead and cleading chemical composition.

介绍了锤头和衬板化学成分的选择.

The chemical composition of the pyrolytic oil was clearly known this way.

由此,全面了解了热解油的族分组成和化学组成.

Here is the report of chemical composition inspection.

这是化学成份检验报告.

The infrared spectra ( IRS ) are measured for chemical composition of series gallstones.

用红外光谱法测量了系列胆结石成分的红外光谱.

The influence of chemical composition on austenitizing temperature was introduced.

介绍化学成分对奥氏体化温度的影响.