Which tense should I use in "I was talking about … when she started to talk about …"?

Question

I was talking to her about something else when she suddenly started to talk about what he had been up to these days.

I was talking to her about something else when she suddenly started to talk about what he was up to these days.

I was talking to her about something else when she suddenly started to talk about what he has been up to these days.

I was talking to her about something else when she suddenly started to talk about what he is up to these days.

Which of the above sentences grammatically correct? What's the difference in their meaning?

Answer 1

The main issue with these sentences is that you shouldn't really use "these days" when using anything other than the present tense.

With regards to the tenses, this is a rather complicated part of English. Because the head verb ("started") is in the perfect tense, you need to imagine all the tenses in the subsequent clause being brought forward by one step (pluperfect -> perfect, perfect -> present).

There are differences in these meanings:

• "I was talking to her about something else when she suddenly started to talk about what he had been up to" - this means what he was doing at some point before she spoke to you (imagine it being in the perfect)
• "I was talking to her about something else when she suddenly started to talk about what he was up to" - this means what he was doing around the same time as when she spoke (imagine it being in the present)
• "I was talking to her about something else when she suddenly started to talk about what he has been up to" - roughly the same meaning as the previous one, but I wouldn't use it personally
• "I was talking to her about something else when she suddenly started to talk about what he is up to" - this one to me feels grammatically incorrect. I would never use the present when the head verb is in the perfect.

Answer 2

All are grammatically correct, and there is little practical difference in their meaning. Noting only the words that change with each example,

"had been up to these days" indicates the actions are in the past, although recent;

"was up to these days" could indicate the actions are in the present and/or near past;

"has been up to these days" indicates the actions are in the near past;

"is up to these days" indicates the actions are presently happening and ongoing.

"These days" keeps all of these examples in the present, recent or near past.

Answer 3

I was talking about something else when she started suddenly talking about what he was up-to these days. In your sentences, suddenly, as in “suddenly started,” is a misplaced modifier.