Generally speaking, is it not possible to indicate 'was' or 'were' on '是‘？

Question

I was listening to this 听力练习 on this beautiful day, staring at the little mountain outside my window. 莉莉：英子，你不是在一家公司工作吗？ I, swift as an eagle, think ‘Yingzi, aren't you working for a company?’ 英子：是的。 I, swift as an eagle, think 'Yes' 英子：5年前，我在公司做秘书，工作强度大，时间长，薪水又不高，挺辛苦的。有了孩子以后，我就辞职了。 I, swift as an eagle, think ‘Wait a minute, Lilly just asked if she worked for a company, and Yingzi said '是的’。 These women are crazy! Yingzi resigned after she had a baby! Go back, listen again. 莉莉：英子，你不是在一家公司工作吗？, 英子：是的。not 英子：没有啊。 莉莉：英子，你不是在一家公司工作吗？here means ‘Yingzi, weren't you working for a company?’ I have looked for and found instances of '是了‘ and '是过’ but I think that the meaning was not to indicate that the given event was somewhere in the past. 他们过去是好朋友, 但现在已不再是了. 整个儿说起来, 我们的日子是过得挺痛快的. Generally speaking, is it not possible to indicate 'was' or 'were' on '是‘ or '在‘？？

Answer 1

Good question! You are dedicated to the language and find its sensitive important questions.

I have looked for and found instances of '是了‘ and '是过’ but I think that the meaning was not to indicate that the given event was somewhere in the past. 他们过去是好朋友, 但现在已不再是了. 整个儿说起来, 我们的日子是过得挺痛快的. 

1,现在已不再是了=现在已不再是好朋友了。so 了 is not combined with 是, but like 刮风了，开始了...

2,我们的日子是过得挺痛快的。It is a emphasize sentence patterns 是...的，nothing with 是过. the phrase is 过得挺痛快，“过” is a verb, meaning to live. 过得挺痛快had a very good time

So, your sentences are not related to the past tense at all.

Is it clear enough for you?

Answer 2

Yes you are correct. There is no straight indication of verbal tenses. You need to consider the scenario described by the whole sentence.