An A is worth four points, a B three points, a C two points and a D one point.

VOA: special.2009.03.05

And the last example that we're going to talk about is thionyl chloride, so it's s o c l 2. This is another good step forward, because now we actually have four different atoms in our molecule.

我们要讨论的最后一个例子,是氯化亚砜，就是硫，氧，氯，二，这又是一个进步，因为我们的分子中现在有四个不同的原子了。

麻省理工公开课 - 化学原理课程节选

So carbon has four valence electrons, so if we talk about c 2, again we're going to start filling in our molecular orbitals, and now we're going to have eight electrons to fill into our molecular orbitals.

碳有4个价电子，所以如果我们考虑C2的话，同样，我们开始填分子轨道，现在我们有8个电子,要填入分子轨道。

麻省理工公开课 - 化学原理课程节选

The team examined results from a Norwegian study of nine hundred fifty-four people with C.O.P.D.

VOA: special.2009.06.03

The C.D.C.also found that carbon monoxide kills more than four hundred Americans each year.

VOA: special.2010.02.02

In nineteen eighty-four, the John F.Kennedy Center for the Performing Arts in Washington,D.C.

VOA: special.2009.11.29

In fact, it was not until nineteen sixty-four that D.C.

VOA: special.2009.03.20