Ok. Got it.

Just showing this again as interested!

I thought that X would happen (said whether X happens or not)

I was certain/sure that X would happen (said whether X happens or not)

I knew that X would happen (said only when X happens)

I suppose 'I was certain' is imperfect tense and therefore the action has not been completed; whilst 'I knew' is perfect tense. But why does the tense of the main verb (pre-result) govern a positive/negative outcome?

It doesn't (unless I'm misunderstanding you). Even in your own examples, each uses the imperfect (thought and knew, and see below re was certain), even as the first two are about uncertain events while the third is about a certain one.

(Note that was certain isn't in perfect tense — that would be has been certain or had been certain.)

Arseface is right. Verb case should match.

She is....who has.

And since we're nits in here, the perfect is not a tense: it is the aspect. Tense is either present or past.

Future?

There is no future.

I am not 100% sure but I think that this is a definitional thing. "Knew" is an action one takes towards the truth; you can't "know" something unless it is true or maybe true. If it may be true then you would say "I know x will happen," if you "knew" something then it must have been true.

The noun clause "that x would happen" is what you "knew" and is modified by your action. Although it pertains to an event happening as its characteristic, it could be anything; e.g. I threw "the ball" - because you threw it, that implies certain properties of the ball, that it is throwable by a person.

Here "knowing" in the past tense implies that the event was true because "knowing" an action you take with regards to an independent thing (the completed event). The event is knowable, therefore it must have happened.

The other verbs - "was certain" and "thought" are a mental action independent of the truth of "that x would happen." You can be certain or think anything, that is your state of mind and has no dependency on the accuracy of it.

Strunk & White

I heard "times it by" (instead of multiply it by) in a commercial last night. Instatilt.

You're wrong.

"is" matches "she."

"have" matches "the girls."

Would you say, "Of all the girls who has passed the class, she is the prettiest one?"

No. It's "Of all the girls who have passed the class, she is the prettiest one."

Therefore, she is "one of the girls who have passed the class."

I'm convinced that the best choice is to leave the have/has out of such sentences entirely. Anytime you can remove extraneous words without sacrificing clarity, it's a good thing.

As for keeping the word in, I consider Strunk and White's reasons definitive. I should have pulled mine off the shelf before giving my initial wrong opinion.

I disagree. I say you're wrong.

It isn't worded like your example. Of course I agree entirely with your example, and also with Strunk & ****e, but the subject in our sentence here is 'she', not 'the girls'.

And the verb is "is." She is. That agrees. She. Is.

"the girls who have passed the class" is its own clause, in which "have" has to agree with "girls."

This is exactly like the S&W example you claim to agree with.

My favorite?

Your welcome

I feel like innocent children are dying when I see it

Swan has you right, "strictly speaking", but says both ways are possible.

I'm cool wi that.

No, no, no, no. Style and rhythm and voice and metrical balance and deliberate movements away from clarity (for deliberate reasons) must be factored in, even in expository prose, unless you're writing ticker-tape copy.

This would be a meaningful pivot if Strunk and White weren't total arsefaces. With all due respect to Arseface.

Yes, those words wouldn't be extraneous then, would they?

The addition of "have" to the sentence being discussed, adds nothing.

As for S&W, I don't think they wrote the bible on grammar but I'd take a critique written by a speaker/teacher of British English with a grain of salt since Elements was quite specifically a guide on writing American English. It's been a useful little book for many when in doubt, including me. The writer you referred to only had issue with a few of the grammar rules anyway, not the style guide.

Tautological definitions of "extraneous" are tautological.

Or here's another angle: there's no such thing as "extraneous words" in the sense you're suggesting: words always add "something"--it is impossible for them not to, being physically present and all--the question is how one judges this ineluctable "something."

In the example under discussion, choosing to include "have" alters the metrical design and/or rhythm of the sentence, how it rolls off the tongue, and (to a slighter extent) what type of voice it possesses--you then judge the fitness of these added effects on a situational basis.

As for Elements: if it has helped, provided comfort, firmed up the nebulous, made straight the crooked, then more power to it, but I'm pompous enough to add this: retire the lovely old crutch if you want to grow.

I must concede, you [have] got me there.

And my sentence probably shouldn't use "got" like that, but it does roll off the tongue splendidly (without the "have").

hmm

you're much better at conceding than i am

this troubles me

wine is called for

When quoting someone else verbatim, is there a way to denote that you understand that you're quoting a grammatical error?

Like if it's a misspelling there's, "Tom wlaked (sic) his dog to the park."

But if there's an incorrect bit of punctuation in mid-sentence like a misplaced comma, is there any way to disown the error and still quote someone verbatim, or are you just screwed?

Same way, it applies to the entire part of the quote preceding it and not just to one word. It means the quote is reproduced exactly as found in the source and the error was present. Your example could be written like this too:

"Tom wlaked his dog to the park. [sic]"

or more to your point:

"Tom walked, his dog to the park. [sic]"

Cool, thank you. I've run into it a few times and usually just end up dropping the quotes and paraphrasing. I'll use that in the future.

if a basketball commentator says "the Heat has played really well tonight" that's wrong right?

shouldn't it be "the Heat have played really well tonight"

No. One team, singular noun.