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

学有两种，双。

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

，也称为西格玛，非常简，它们所附着的原子可以围绕自由旋转。

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或三以插入各种原子，只在之间留下个。

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，原子就会很容易地附着在合物分子上，将双转为。

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) .

羧酸是种有机合物，其特征是个（C）原子与个氧（O）原子双结合，并与个羟基（-OH）结合。

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合物组成的，它有分离的链，相对于氧原子而言，些含有双。

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合物：所有的烷烃，含有双的烯烃，含有个或多个三的炔烃。