In the following sentences, the boldfaced coupular verb is found in a clause within a counterfactual clause. Should "are" or "were" be used? Why?
Imagine a 100-story skyscraper without an elevator. People whose offices were/are on the 60th floor would have to spend lots of time walking up and down every day.
I feel as if I were standing on the edge of a cliff toward which thousands of horses were/are rushing.
People whose offices were/are
"Were" is the fake past tense used for counterfactuals and it looks like the proper choice.
"Are" is the simple present. In practice, you may hear this used because it's simpler. Sometimes people avoid complicated grammar structures, even when they would be appropriate.
thousands of horses were/are rushing
The counterfactual "were" already appeared earlier in the sentence: "as if I were standing". Repeating "were" yet again seems to be overkill, so "are" is better.
In your first example I would use neither were nor are. The verb imagine dictates the use of would be, as there is no use of if in the sentence. "would be" has exactly the same function as "would have to":
Imagine a 100-story skyscraper without an elevator. People whose offices would be on the 60th floor would have to spend lots of time walking up and down every day.
As for your second example, were is correct, as it preserves the counterfactual character of the sentence. Using are would transfer the meaning of the sentence into reality, which is not coherent with the beginning. There are no actual horses rushing towards a cliff.
I feel as if I were standing on the edge of a cliff toward which thousands of horses were rushing.
