These are of two varieties, known as single and double bonds.

学键有，键和双键。

Single bonds, also called sigma bonds, are pretty simple, and carbon atoms attached by them can rotate around the bond freely.

键，也称为西格玛键，非常简，它们所附着的碳原子可以围绕键自由旋转。

Certain reactions open up a double or triple bond to insert various atoms, leaving only a single bond between the carbons.

某些反应会打开个双键或三键以插入各原子，只在碳之间留下个键。

But once that's done, the hydrogen atoms readily attach to the hydrocarbon molecule, converting a double bond to a single bond.

但是旦完成，氢原子就会很容易地附着在碳氢分子上，将双键转为键。

Carboxylic acids are a type of organic compound characterized by a carbon (C) atom doubly bonded to an oxygen (O) atom and singly bonded to a hydroxyl group (-OH) .

羧酸是有机，其特征是个碳（C）原子与个氧（O）原子双键结，并与个羟基（-OH）键结。

It's made of a polymer called " polyethylene terephthalate" , which has rings of carbons separated by chains of carbons, some of which have single and double bonds, to oxygen atoms.

它是由聚对苯二甲酸乙二醇酯聚组成的，它有分离的碳链，相对于氧原子而言，些含有键和双键。

So three words representing three different groups of organic compounds: alkanes for all single bonds, alkenes if they contain double bonds, and alkynes if they contain one or more triple bonds.

所以三个词代表三组不同的有机：所有键的烷烃，含有双键的烯烃，含有个或多个三键的炔烃。