"That is/That are" when is right, when is wrong?

[asker]

I have long been confused about this relative phrase. Rules, and also experiences from most questions tell me “that is/that are” is wrong, redundant, wordy, not concise, majority from OG's explanation.

Here are some contradictory examples:
1) From Ron's video: https://vimeo.com/31215402, around 37'. See screenshot below:

Ron said "that they are" is wrong. Because it implied that they are collecting days.

2)
OG13-7, option B and C
"that are" is wrong here.
The same error applied to OG13-28A, OG13-43-C, OG13-60-E(that was), OG13-72-E, OG13-82-C, OG13-83-D, OG13-86-C, OG13-106-E

OK, it seems a perfect rules although there is little tricky on OG13-68.

3)
When I applied the rules to OG13-68, option E, it seems worked at first:
OG said "plan itself cannot do the action of “cut”".
OK. "that are" is wrong here again.
But actually in E, it’s “that are to cut”, so “plans are to”, plans’ object is to do sth, why wrong?

Then, let's look at something else:
4)
Did we just mentioned OG13-86 above? Yes, if we looked at the correct answer OG13-86-B, "a phenomenon THAT IS explained" turned out to be a correct answer!

More importantly,
5) OG13-96-D
"a body of work THAT WAS rooted" is right again!

6) OG16-52-original-sentence
"50 drugs that were advertised" is obviously right since it's not underlined.

7) OG16-137-A
“17 nearby stars that”

I don't know how to understand this contradictory. Can any instructor help to resolve the paradox?

Thanks in advance.

[RonPurewal]

what, exactly, is your question? i can't tell.

please clarify what you are trying to ask. thank you.

[RonPurewal]

even though i can't tell exactly what you are trying to ask here, a couple of things may be relevant:

1/
are you considering the intended meaning?
it seems you may not be thinking (enough) about intended meaning.

'that' can do many different things. for instance:
* it can be the object of the stuff after it (the book that i read yesterday)
* it can be the subject of the verb after it (the book that was on the chair)

some of these examples seem to be irrelevant to others, since the meanings are not the same.

[RonPurewal]

2/

also experiences from most questions tell me “that is/that are” is wrong, redundant, wordy, not concise, majority from OG's explanation

remember!
the OG answer keys are usually incomplete—and quite often wrong.
the keys are subcontracted to people who are, to be blunt, nowhere near as good as the problem writers. in many cases they just don't know how to explain how, or why, something is incorrect. (to be fair, good explanations are not very easy to find.)

if OG says that something is 'wordy', 'awkward', etc., this really just means the writer didn't know how to explain why the choice is actually wrong.

also of note is that the OG rarely mentions meaning issues.
quite often, the OG will correctly mention that something is 'wrong'—but WON'T mention WHY it's wrong. most often this will happen when the reason has something to do with meaning.

[RonPurewal]

and...

3/
OG is a banned source here.

this extends not only to the text of the problems, but also to discussion of the problems.

it does not mean "let's just ask about OG problems without quoting them", as that would render the whole prohibition meaningless.

thank you.

(if you have targeted questions that are mostly based on OG problems—as you do here—this would be an excellent agenda for a private tutoring session.)

[asker]

I think my problem here is formalism.
As your bullet point 1, not thinking hard enough to distinguish the usage of "that". So whenever I saw a structure of "that is/was/are/were" in the options, just automatically eliminate them as wordy.

[RonPurewal]

'wordy' is NOT a formal concept.
...so, if you're thinking along those lines, then, ironically, your thinking might not be 'formal' enough.