help me understand this comma stuff...

<p>I am struggling with ACT English... especially about comma usage... </p>

<p>1.
My grandmother tried to explain that "Miami time" referred to those moments when time seemed to slow down or stand still.--> correct one</p>

<p>My grandmother tried to explain that "Miami time" referred to those moments, when time seemed to slow down or stand still. --> comma before when is wrong....</p>

<p>2.
I could sense it falling to the tile floor, certainly in the path of some kid's foot.-->correct one</p>

<p>I could sense it falling to the tile floor certainly in the path of some kid's foot.--> no comma before certainly is wrong...</p>

<p>3.
Even as car makers work diligently to improve safety on the road, particularly during night time driving, no device can replace the vigilance and skill of the driver.--> this is correct one</p>

<p>Even as car makers work diligently to improve safety on the road particularly during night time driving, no device can replace the vigilance and skill of the driver.--> this is wrong...</p>

<p>I can't understand how these sentences are different and why one of them is right...</p>

<p>In participle sentence, for example..
My dad brought a cooked turkey, dressed in green pants.
--> this means.. Dad who wore green pants brought turkey....
My dad brought a cooked turkey dressed in green pants.
--> this means,, Dad brought turkey that wore green pants... </p>

<p>Like this... Do meanings of above sentences become different when comma is used?
or... because comma sentences are not important, comma is used??</p>

<p>I can't understand this.. thing....</p>

<p>and lastly...
4.
It is a social music that performed at weddings, birthday parties, and feasts.</p>

<p>It is a social music, performed at weddings, birthday parties, and feasts. </p>

<p>--> Do these two sentence have different meaning? I think grammar of both of them is right...</p>

<ol>
<li>My grandmother tried to explain that “Miami time” referred to those moments, when time seemed to slow down or stand still. -> This is wrong because the comma there is unnecessary. Seriously, say this to yourself. It does not make sense. Does it? The grandmother is describing “those moments;” she is not in the time “when time seemed to slow down or stand still.”</li>
<li>I could sense it falling to the tile floor certainly in the path of some kid’s foot. -> This is a run-on sentence without the comma like #3.</li>
<li>Even as car makers work diligently to improve safety on the road particularly during night time driving, no device can replace the vigilance and skill of the driver. -> This is wrong because again, it’s a run-on sentence. Say it aloud to yourself. Does this make sense to you?</li>
</ol>

<p>And yes, depending on where you put commas, each sentence becomes different in meaning.
You really need to pay attention to the commas. They are the trickiest.</p>

<p>I am not sure about #4, but what I think is that this sentence, “It is a social music that performed at weddings, birthday parties, and feasts,” is wrong. The social music cannot perform at weddings. You need a person/performer to do so.</p>

<p>By the way, I am taking the test on September for ACT, and let’s hope we can do this. :)</p>