Learn English – How to ask the “distance between the position and the position that’s required”

Either is legitimate and would be understood.

“What day is tomorrow?” appears to be more popular:

But neither is more popular than Jim’s suggestion above of “What’s tomorrow?”:

It’s difficult to know how much weight to give the graphs above. For one thing, “What’s tomorrow?” is much more flexible contextually. For example:

“What’s tomorrow?”

“Your dentist appointment.”

This response would not be legitimate for either of the other forms of this question.

If I had to speculate, I’d say that “What day is it tomorrow?” is avoided for a few reasons, including the suspicion mentioned in the comments above that it doesn’t sound quite right to pair the definitively present-sounding “is it” with the decidedly futuristic “tomorrow”. There’s also the simple fact that the word order causes the speaker to all but ask a different question (“What day is it . . .”) before asking the intended question (“. . . tomorrow?”).

In the end, probably having to do with the fact that the concept of tomorrow depends on a reference point of today, people are comfortable asking about it in the present tense.

Personally, if I wanted to know which day of the week it was going to be, I’d ask:

What day is it tomorrow?

Like many things in English, there isn’t a hard and fast rule here. Choose what feels right to you.

"How is she?" is a perfectly fine and quite common way of asking about someone, when you are interested in either their health or in their emotional state.

The meaning is the same as the phrase "How are you?" when used as a greeting. In fact, you can use "How are you?" beyond the polite formula, in situations where someone is (for example) bereaved, and you are sensitively showing your interest and concern.