Hey —
The “Could be…complete list” and vice-versa reading challenges are tough and common, and that’s a reason I try to emphasize them in the book — they will show up in a variety of contexts (the most common being the “Rules Questions” you brought up, which do come at the beginning of the vast majority of LSAT games) — so you want to make sure you understand the separate meanings of these phrases conceptually — that you can pretty much “visualize” the difference — that way you can feel confident that you can apply what you know correctly in a variety of situations —
So, imagine a situation with five friends – Jack, Ken, Louise, Mary, and Nicole – and a car that only seats four – specifically, in the driver’s seat, the passenger seat, and two seats in the back row. And we know exactly one person will ride in each seat (4 people total).
If we had no other rules, and got the question:
“Which of the following is a complete list of people who could sit in the back?”
Any one of these friends could sit in the back, and so (again, in the absence of any other restrictions) the right answer to this question would have to list all the friends, because they are all possibilities.
If we had no other rules, and got the question:
“Which of the following could be a complete list of people who sit in the back.”
In this case, we know that any correct and complete list of people who sit in the back row would be limited to exactly 2 individuals, because exactly 2 individuals will sit the back row.
So, if we are asked for one answer that could be the correct listing of these individuals, the right answer would include just two people, and an answer that lists everyone could not be right, because they can’t all sit in the back at once.
Again, that is the fundamental difference between the two types of wordings, and if you can understand it in that way, you can apply that understanding to questions that differ in other ways from one another —
So, if we instead got the question —
“If Jack drives, which of the following is a complete friends who could sit in the back?” —
The right answer would include all possibilities remaining — all friends other than Jack — because all those people could still sit in the back, and the question asks us to list all possibilities.
And if we got the question —
“If Jack drives, which of the following could be a complete list of friends who sit in the back?” —
Again, in this case, we are being asked about what could be an actual combination of the friends in the backseat — since we know that there are only two seats in the back, and we know that Jack is driving, we would know, in this case, that the right answer would have to include exactly two people, and the pairing can’t include Jack.
The q you brought up is akin to this last example — we are not asked to find every possible person who could work the second day, but rather one potential specific combination.
I hope that helps clear it up —
One final related point I want to make — in terms of the last two examples — the ones involving “If” — a big point of difference between the simplified example I gave and a real LSAT problem (like the one you brought up) is that every time you are given a conditional to start a q “If…,” — that conditional is meant to lead you on a chain of inferences — that is, knowing that given information, and combining it with what you already know, will lead you to making an inference, which will lead you to making another inference, and another, and so on — and it is these inferences that will directly impact what to expect in the right and wrong answers —
So, you want to make sure to focus first on inferences, try to play it out as fully as you can, and then think super-carefully about whether that particular q is asking for a complete list of all those that could, or asking you to list one possible combination —
HTH — please know that these “could be” issues fall into the category of “seems simple enough but gets everyone all turned around” and so if you have any follow up just let me know and I’ll be happy to try and help further — MK