Usage of mixed conditionals - past/present

Question

The thing I don't understand about mixed conditionals is this example from my book:

A. “If Anna were here, she would've known what to do.” (but Anna's not here, so she can't help us.)

It says before that that mixed conditionals, where there is this type: Past simple - would + have + past participle, usage is: unreal present situations, usually imaginary permanent states, which could have had some consequences in the past.

In my language, you cannot possibly have some present situation that had / can have consequences in the past. How is this possible?

Can someone simplify the usage?

I have these questions:

B. If you (wear) a beard all the time, they (not recognize) you without it.

I believe it should sound like this:

If you wore a beard all the time, they wouldn't have recognized you without it.

Just because it sounds natural, but not because it might be correct. Can someone explain the usage listed above (in B)? What I'm thinking is: if you wore a beard—that's imaginary, not real now—they wouldn't have recognized you without it; meaning that in the past it could've had some consequences if you did and were like this like you are today. (Which you aren't actually.)

C. If the Earth (stop), everything (be) changed in the world.

I believe that this is the answer:

If the Earth had stopped, everything would be changed in the world.

but why wouldn't it be this?:

If the Earth stopped, everything would have been changed.?

If it stopped, it's not moving, then this could've caused changes in the past?

D. She (win) the beauty pageant if she (wear) different clothes.

This is my answer:

She would win the beauty pageant if she had worn different clothes.

Because here we have some past event—wearing different clothes—which causes the victory ... and she would've just won it - but she didn't, because she hadn't worn different clothes. They are probably talking about it after but near the end of that competition.

Were these right explanations? If someone could, please summarize the usage of these 2 mixed conditionals (past simple - would + perfect infinitive, and past perfect - would + infinitive).

EDIT: I found another sentence I'm not sure about - it says I should comment on it (in mixed conditionals, only the 2 types I listed above):

E. They are injured because they were driving very quickly.

I'd say here:

If they hadn't driven (or maybe "been driving") very quickly, they wouldn't be injured.

Because it's a past event... but when I think about it, even though it's obviously not a "permanent state", but you could say:

If they didn't drive very quickly, they wouldn't have been injured.

I really can't tell the difference when I look at the usage box in my book.

Answer 1

Compare
(A) "If Anna was here, she would've known what to do."
(B) "If Anna had been here, she would've known what to do."

In (A), the speakers are currently considering what to do and lamenting that Anna isn't with them right now, because she would have been able to help them.

In (B), the speakers are discussing a past situation (we don't know how recent) where Anna's absence left them with no solution. The opportunity to do the right thing has now passed.

I think if you see the difference between the two, that will go a long way to helping you with similar constructs.

"If you (wear) a beard all the time, they (not recognize) you without it."

All the below are possible:
(A) If you wore a beard all the time, they would not recognize you without it.
(B) If you had worn a beard all the time, they would not have recognized you without it.
(C) If you were to wear a beard all the time, they would not recognize you without it.

(A) Can be used in a past sense, in a kind of confirmatory way: Given that you always wore a beard, then of course they wouldn't recognise you without it. But it can also be a suggestion for the future: if>then. (B) In the past period referred to, he wasn't in the habit of wearing a beard, and therefore had no chance to pass unrecognised by removing it.
(C) More specific than the second sense of (A). Making a hypothetical suggestion concerning a group of people currently unknown; implying that at the moment he doesn't wear a beard all the time (or at all).

Answer 2

I agree with you. In fact, I see two problems.

Your example:

A. If Anna were here, she would've known what to do.

The given explanation of how to interpret this: Anna's not here, so she can't help us.

The given explanation of how to use the construction in general: unreal present situations, usually imaginary permanent states, which could have had some consequences in the past.

Problem 1: the two explanations are contradictory. With this interpretation, the sentence isn't about the past at all. However, consider a different interpretation:

Suppose Anna isn't here because she didn't understand the procedure for paying for her train ticket (a common problem in my country). If she were here, she would have known what to do.

I believe this is the kind of interpretation the explanation of usage refers to. It also matches the explanation and example in Wikipedia:

If I were a woman, I would have entered the contest.

You ask: how can the present have consequences in the past? Well, it cannot cause anything in the past, but it can imply something in the past. The consequences are logical consequences.

Problem 2: if we go back to the given interpretation, the given explanation of usage does not apply. So how can we still have a perfect tense? Why don't we need to say:

A'. If Anna were here, she would know what to do.

The answer to that is given by toandfro: here, we can use the perfect tense to indicate that the chances of knowing what to do have passed.

Answer 3

If Anna were here, she would've known what to do.

This means "if Anna were here" in a greater, pervasive sense which extends over the entire period which covers the past event during which it was important for someone to know what to do, as well as the present.

The wording suggests that the event is in the fairly recent past.

It is not interpreted as meaning "if Anna were here now, specifically at this moment, she would have known what to do in a previous moment, when she wasn't here" which doesn't make sense.

It would not be used in discussing something which happened, say, ten years ago. Then it would be

(That day ten years ago) if Anna had been here, she would have known what to do.

But imagine that the event happened only five minutes ago. Perhaps it is in a work place and Anna took the day off.

You sure made a mess of things just now! If Anna were here, she would have known what to do.

[If Anna were here (at work today) she would have known what to do (five minutes ago, when you messed up).]

Anna being here is with regard to a broader scale of time than the minute-by-minute scenario of the mishap.

In my language, you cannot possibly have some present situation that had / can have consequences in the past. How is this possible?

Translate the above to your language and you will have the answer. How do you tell someone that if Anna were here today (if she had come to work at 9 a.m. instead of taking a day off), she would have known what to do during the emergency which happened 15 minutes ago (at 1:30 p.m.)

It's possible that there is no translation to your language which specifically has that meaning, so that context is required to clarify it.

In general, if some grammatical tense distinction is missing in a language, you can make up for it with explicit indications of time or some additional context (which is the medicine that cures all sorts of semantic ailments).

Continuing with your examples:

If you wear a beard all the time, they will not recognize you without it.

If you wore a beard all the time, they wouldn't recognize you without it.

If you had worn a beard all the time, they wouldn't have recognized you without it.

If the Earth stops, everything will be changed in the world.

If the Earth {stopped | were to stop}, everything would be changed in the world.

If the Earth had stopped, everything would have been changed in the world.

Note that "be changed" is awkward, especially in this last one. For one thing, the cause of the change is clear: the change is caused by the Earth stopping. The passive voice "to be changed" is used when the agent of change is unknown, or we wish to conceal it. In this case, the natural way to express it is from the point of view that changes are taking place globally, by themselves, in response to the Earth stopping: in other words, the reflexive form of "to change".

If the Earth stops, everything will change in the world. [ Much better! Things will change, by themselves, but in response to or as a result of the stopping.]

If the Earth {were to stop | stopped} everything would change.

If the Earth had stopped, everything would {have changed | be different now}.

You ask:

but why wouldn't it be this?:

If the Earth stopped, everything would have been changed?

Because this situation doesn't support the multiple scales of time, like the situation with Anna not being here. The Earth stopping is a sharply defined event, and it is the cause of change. We regard these things as being ordered on the same time scale.

Here is how we can make it similar to the situation with Anna:

If the Earth were rotating, things would not have changed.

[If the Earth were rotating now, it would have been rotating previously at that point in time when things changed. i.e. If the Earth hadn't stopped, things would not have changed.]

This may be the key to unraveling these present tense subjunctives combined with past clauses: negate them.

For instance "If Anna were here, she would have known what to do." What is the negative way of saying "If Anna were here?" Try:

If Anna hadn't taken today off, she would have known what to do.

You ask:

If it stopped, it's not moving, then this could've caused changes in the past?

No.

The last example, in various tenses:

She will win the beauty pageant if she wears different clothes.

She would win the beauty pageant, if she {wore | were to wear} different clothes.

She would have won the beauty pageant, {had she | if she had} worn different clothes.