Usage of “already” and “yet”

Question

I want to know the difference between already and yet in this example:

I was surprised that they had __ to decide what to do.

My answer on this question was already and my teacher marked it as a wrong answer in the test.
What's the difference between already and yet in that sentence?

Answer 1

This is rather tricky. Had the question read:

I was surprised that they had __ decided what to do.

then the answer would be already.

There's no simple answer to this question, partly because of the different ways the word yet can be used. Macmillan lists seven definitions for yet, along with three phrasal uses. It's one of those phrasal uses being referenced in the test question:

We could add to that list of examples:

I am surprised that they have yet to decide what to do.

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As to your question about the differences between the words, some of their meanings can be very similar. (NOAD defines yet as up until the present, while defining already as before or by now – that's a very subtle difference!) However, other usages of the two words differ. For example, if I said:

Have the guests arrived yet?

that would imply that I don't know whether or not the guests have arrived. But if I said:

Have the guests arrived already?

that would imply that I realize the guests are at the doorstep, but I'm a bit surprised by how early they've arrived. Why the difference? NOAD lists this additional meaning for already: as surprisingly soon or early as this.

There are additional ways the two words can be used, yet I can't list them all here.

Answer 2

"Already" means something HAPPENED sooner than expected.

And in your example, the presence of the infinitive "to decide" eliminates the possibility of using "already."

If the second clause was either just a plain past or past perfect phrase, it would be possible to insert "already" there:

I was surprised that they already decided what to do.

I was surprised that they had already decided what to do.

"Yet," on the other hand, is a good fit because "yet" means a period UNTIL NOW. It's often used to show the speaker's expectation for something to happen:

He hasn't arrived yet.

We don't know yet.

Have you eaten lunch yet?

And so:

... they had yet to decide what to do.

Answer 3

I was surprised that they had __ to decide what to do.

In this sentence, yet would indicate something that has not happened (i.e. they have not decided what to do) whereas already would mean the opposite (they have decided).

The sentence would have to be restructured to use already.

I was surprised that they had already decided what to do.

I was surprised that they had decided what to do already.

For a non-native speaker, it might be difficult to see or hear how already doesn't "fit" in the original sentence. One way to keep the difference in mind might be to imagine the following dialogue:

Bob: Did it already happen?

Jill: Not yet!