This Magoosh ACT science [English!] test is very, very important because it is about perhaps the most important category of grammar that is tested by the ACT, and that is the comma. There are so many questions on commas on this test. So it's a really, really important video to be paying extra special attention to, if you struggle with commas at all.

So let's start by going over the three major uses of commas. So the first major use of a comma is to set off a dependent or 从属条款。现在，我知道我在这里使用这种技术语言依赖于 从属条款，你实际上并不知道他们在行动中呼吁是什么，你只需要知道如何识别它们。

I'm using them here for a3 simplicity and, and creating a list of things that commas are used for. But we're gonna go through some examples, so don't worry, you'll be able to see what I mean in just a moment. The second major use of a comma is to create a compound sentence with a conjunction, specifically what's called a coordinating conjunction.

And we will go through specifically what the coordinating conjunctions are in a minute. Again, you don't need to know what they're called. You just need to know how to recognize them. And finally, the third major use of a comma is one you see all the time, and that is to separate lists of items.

So let's talk about number one first. Setting off dependent or subordinate clauses. 所以有一些不同类型的条款。再次，我在这里使用的术语只是为了你想要在语法中徘徊 我和我有点讨论，或者只是为了帮助在这里的类别中创造一些清晰度，但你不需要知道他们所谓的东西。

You need to focus primarily on the examples and that will be just fine, for the purpose of the ACT. So we can use commas to set of what are called appositives, now, appositives are pretty important to an everyday ACT, because your gonna see that tested hm, 可能在每次测试中至少几次。并且一个安排是一个名词或名词短语，用于重命名另一个名词。

So for example, my cat, a purebred Persian, acts like a feral dog. So a purebred Persian. 纯种波斯雷尼猫在这里。它描述了它。 我们使用逗号将其脱离，因为它是额外的句子的信息，但这不是必不可少的。

所以句子可能是，我的猫像野狗一样。但是什么创造，你知道，一点点幽默，或 a little bit of irony in this situation, is the fact that it's a purebred Persian. So the writer wants to put that in to say my cat, even though it's a purebred Persian, still acts like a feral dog. So we're setting them off with comma, since it's extra information.

这里可以在这里与逗号出发的第二类，是参与者，参与者。 Let's look at an example. Looking every bit like a madman, my brother leapt from his bed and 一旦他意识到他为他的考试睡过头就会出门。所以，这是一个演称，它开始描述我兄弟的句子。

Now, this is something you'd also wanna be watching out for when you are dealing with a misplaced modifier question. 因为在句子的主要部分之前，这里的这句话在这里，需要描述什么开始句子的主要部分，所以 in this case it's correct. My brother is looking every bit like a madman, but 因为这是在句子的主要部分开始的额外信息，它从我的兄弟开始，它被逗号掉了。

逗号帮助我们暂停，休息一下，呼吸。所以当我读了我们的句子时， 看起来像一个疯子，我的兄弟从他的床上跳了起来。这是自然的，我们想在那里暂停，所以我们不仅仅是经营所有的话 together and losing track of, losing the clarity of the sentence. So another comma used, setting off a clause here.

It is setting off a subordinate clause. So, for example, until I carefully checked under the covers for spiders, my sister refused to get out of bed. So, this is something that needs to happen before my sister gets out of bed, 直到我仔细检查蜘蛛的封面，所以再次，这里重要的是它不一定被称为什么，但我们的事实 have a main part of the sentence that can stand alone as a sentence.

My sister refused to get out of bed, or get into bed, but I eh, need to carefully check under the covers for 蜘蛛，她不会这样做，直到我这样做，所以这是一些额外的信息，有助于描述我姐姐拒绝睡觉的原因。 然后我们再次拥有相对条款。例如，我在封面下仔细检查了 我的妹妹，谁害怕蜘蛛。

所以这是一个修饰者，它描述了妹妹。妹妹是害怕蜘蛛的事。 But again, the important thing is we have a main part of a sentence here that can stand alone as a sentence. I carefully checked under the covers for my sister. And then we have some extra information we wanna add to describe that sister, and it needs to be set off with a comma in all of these instances.

好的，所以我想在这里提出一些重要的东西，这是逗号，那就是逗号，那就是谁。 Because this is something you'll also, the wondering about on the test. So you should use commas before which but not before that. 例如，那些我从未试图观看的电影是我姐姐的最爱。

But the movies that are my favorites are the ones with lots of action in them. So why is there a difference here? 原因是因为它用于制定被认为对句子的基本含义不是必不可少的信息。 但是，当这对句子至关重要时使用。所以回到这个例子，那些电影， which I've never even attempted to watch, are my sister's favorites.

在这种情况下，作者考虑到它是，您知道，还有额外的信息，对句子的含义不是必不可少的。 在第二个,我们想要确定,或命令er wants to be sure that the reader knows that the movies that are my favorites, his favorite movies, or her favorite movies, are the ones with lots of action in them, so this is essential. It's essential information to the meaning of the sentence, and so we use that.

因为它用于脱离非基本信息，然后我们用逗号或逗号设置它， 因为请记住，当你用逗号设置的东西时，你基本上说这是我添加到句子中的一些额外信息。 Now when you have who, it's a little bit trickier. It depends on whether or not the description is essential.

So for example, the teacher who has always been my favorite decided to retire this year. 我的老师是否从来没有成为钢铁的规则，让我们在房间里扔纸，并在办公桌上跳舞。 So with who, you're making a decision about whether or not it's essential or not.

没有一个艰难而快速的语法规则。但别担心这个行为不会要求做出关于什么的决定 无论是哪些，那样，或者，基本信息或在测试中都不是必不可少的信息 But it will ask you to punctuate that correctly. So, if we have which we need to have a comma before it.

If we have that, we do not want a comma before it. And with who, it could go either way. All right, so let's talk about the second big category of comma usage now, and that is to create compound sentences. 因此，当您使用逗号和所谓的粉丝时，这是一个缩写，帮助您记住，以及，或者，但是，但是，但是，但是，但是，但是，但是，但是，但是，也是缩写。

You wanna memorize these conjunctions. And the reason is because the ACT will often put another word after a comma 这不是这些粉丝中的一个，这将是错误的。所以你真的想确保你知道这些 七个连词可用于创建复合句。例如，这里是正确使用逗号和结合。

我从来没有学习语法,所以我爱rlooked that part of my ACT preparation. So here we have a comma and we have one of the FANBOY conjunctions. Now most students, and, and, but or, or are used a lot more frequently and so they know those are conjunctions, so don't forget about for, yet, and so. Those are also coordinating junctions.

Here's something that would be wrong and this is something that the ACT definitely tests. 我从来没有一个学习语法，因此我忽略了我的行为准备。 因此是过渡，但它不是这些粉丝中的一个，因此你不能将两个句子链接到它们可以单独站立。

So this would be wrong, this would be a comma splice, not a correctly constructed compound sentence. All right. Let's go on to number three, and that is to separate lists. So for example, fishing, hiking, and camping are my favorite summer activities. Now sometimes students want to know if they should have a comma here or not.

无论是逗号还是与美国与英国英语风格有关。 The ACT won't test you on that, so don't worry about that aspect of it. Just make sure you are effectively setting off a list with commas. 让我们来看看测试列表中逗号使用的示例测试问题。大多数大型零售商发布了他们的黑色星期五广告扫描，优惠券和优惠 在线提供消费者的时间，了解销售并计划购物。

Okay, so this sentence is testing commas. It's testing commas, 具体来说，在一个列表中，因为我们在这里有一系列内容。我们有广告扫描，优惠券和优惠。 But what it is testing is what's supposed to go on this list. We've got this weird comma here.

Is offers online to give, is that one thing that's supposed to go on the list, and then consumers is another thing that's supposed to go on the list? Mm, I don't think so. So let's take a look and see if we can punctuate this correctly. So answer choice B has ad scans, coupons, and offers, online to give. Now there's no comma here, but remember that A, C不会会测试您。

What makes this wrong although it usually will put that comma there. What makes it wrong though is that fact that this comma here is being placed between offers and online. So we don't wanna have a comma there, 这只是将主题分开，从动词尴尬地分开。我们希望确保此列表已正确分开。

广告扫描，优惠券和在线提供给消费者的时间，所以我们不想在其他地方有一个奇怪的逗号。 And so that means our answer is D, which properly punctuate that list with commas. So, once again, the three major uses of commas. To set off dependent or subordinate clauses. Let's just call that setting off clauses.

Setting off bits of information that are extra to the main part of the sentence. Remember, what's set off by commas whether it's at the beginning, the end, or in the middle always needs to be able to be lifted out of the sentence, and we should still have that main part of the sentence there. Two, to create compound sentences with a coordinating conjunction, remember those are your FANBOYS, memorize those seven conjunctions.

最后，对于很多学生来说，这是最简单的，分开列表。