<p>OK. Silverturtle has convinced me to change my answer. The mention of the prepositional phrase reminded me that removing it should not change the conjugation of the verb.</p>
<p>In that case the correct grammar would be, “Is either going to Costco…?”</p>
<p>conjugating “to be” seems to give a lot of people trouble.
I often hear “I be knowing him for 5 years” when they mean “I have known him…”
And posessives give people trouble too. “My baby father” comes to mind. Those that use that don’t mean an infant that has become a father, they mean “the baby’s father” as in an unmarried couple so estranged that they don’t even use terms like ex-husband or ex-boyfriend to refer to the man that got them pregnant.
Sometimes people even have trouble with the “t” sound. “Si-in” means sitting, and “sa-in” means satin.
I am one that uses too many “ats” As in “Where do you want to meet at?”
And according to earlier explanations, Closetotheedge has misused “effect” in post 37. Edge was indicating the word “you” had no influence on the subject/verb agreement, and so that would call for “affect”.</p>
This reminds me of another pet peeve. When did people start referring to your “Social Security Number” as your “Social?” As it, “What’s your Social?” I can’t stand that.</p>
<p>As for “bring” and “take,” I can’t help, because growing up in the South, we used “carry” instead of these verbs. As in, “I’m gonna carry Mama up to the store to cash her check.”</p>
<p>It’s not “this [particular] YOU,” or “that [particular] YOU.” It’s “either ONE of you.” So, the verb has nothing to do with being conjugated with the second person, but, indeed, with the third person, because it refers to “either ONE of the two of you.”</p>
<p>Younghoss, I do not believe I misused effect. I wrote, “and so the you has no effect on the subject/verb agreement.” Effect in this sentence is a noun and the object of has, and so “effect” is the correct ussage here. If I wanted to use a verb I could have written, “and so the you does not affect the subject/verb agreement,” in which affect is a verb used with does.</p>