carbon

Carbon has a valency of 4 .

碳的化合价是4价。

We all need to look for ways to reduce our carbon footprint .

我们都需要寻求降低碳排放量的方法。

Reducing levels of carbon dioxide in the atmosphere is of critical importance .

减少大气层中的二氧化碳含量极其重要。

Humans take in oxygen and breathe out carbon dioxide .

人吸入氧气，呼出二氧化碳。

A spokesperson commented that levels of carbon dioxide were very high .

发言人称二氧化碳的含量很高。

She is a carbon copy of her sister .

她跟她姐姐长得一模一样。

The two principal combustion products are water vapor and carbon dioxide .

两种主要的燃烧产物是水蒸气和二氧化碳。

Diamond is the crystalline form of the element carbon .

钻石是碳元素的晶体结构。

Carbon dioxide is a necessary result of the oxidation of carbon compounds .

碳化合物氧化后必然会产生二氧化碳。

The drawing is transferred onto the wood by means of carbon paper .

这幅画是通过复写纸印到木头上的。

Plants absorb carbon dioxide from the air and moisture from the soil

植物从空气中吸收二氧化碳并从土壤中汲取水分。

In its untreated state the carbon fibre material is rather like cloth .

原始的碳纤维材料很像布料。

Plants and trees filter carbon dioxide out of the air and produce oxygen .

花草树木会过滤掉空气中的二氧化碳并制造氧气。

Dissolved carbon dioxide makes the water more acidic .

二氧化碳溶解后能使水的酸性增加。

The proposed initiative would mandate a reduction of carbon dioxide of 40 %

倡议将强制规定把二氧化碳排放量降低40%。

Methane is often regarded as the second most important greenhouse gas after carbon dioxide .

甲烷常被认为是仅次于二氧化碳的重要温室气体。

She 's a carbon copy of her mother

她和她妈妈就像是一个模子里刻出来的。

Carbon dust and oil build up in large motors and cause them to short-circuit

碳尘和燃油在大发动机里越积越多，造成了发动机短路。

Industrialized countries must reduce carbon dioxide emissions .

工业化国家必须减少二氧化碳的排放。

The limit for carbon monoxide is 4.5 per cent of the exhaust gas .

尾气中一氧化碳的排放限量为4.5%。

He inserted the paper and two carbons .

他放入了那张纸和两张复写纸。

Organic compounds contain carbon in their molecules .

有机化合物的分子中含碳。

This may provide a quick and accurate way of monitoring the amount of carbon dioxide in the air

这也许能提供一个监测空气中二氧化碳含量的既快又准的方法。

In graphite sheets , carbon atoms bond together in rings

石墨层中的碳原子相互连接形成碳环。

Theresa 's first marriage was almost a carbon copy of her parents ' .

特雷莎的第一次婚姻简直就是她父母婚姻的翻版。

Carbon , hydrogen and oxygen combine chemically to form carbohydrates and fats

碳、氢、氧化合形成碳水化合物和脂肪。

Under normal circumstances , these two gases react readily to produce carbon dioxide and water .

在正常情况下，这两种气体容易发生反应产生二氧化碳和水。

The amount of carbon dioxide released by human activities such as burning coal and oil is small in comparison

相比之下，人类活动燃烧煤、石油等所释放的二氧化碳要少一些。

A methane molecule is composed of one carbon atom attached to four hydrogens .

甲烷分子由1个碳原子与4个氢原子构成。

The emission of gases such as carbon dioxide should be stabilised at their present level

二氧化碳等气体的排放应该稳定在当前水平。