Past + Conditional clarification

[yo4561]

The All the Verbal book provides a correct example for the use of Past + Conditional below:
The scientist BELIEVED that the machine WOULD BE wonderful.

However, I have seen something along the lines of this example below deemed as correct:
The scientistic is optimistic on the team's R&D breakthrough, signaling that the machine would be wonderful.
Doesn't this mix present + past incorrectly?

[Whit Garner]

The All the Verbal book provides a correct example for the use of Past + Conditional below:
The scientist BELIEVED that the machine WOULD BE wonderful.

However, I have seen something along the lines of this example below deemed as correct:
The scientistic is optimistic on the team's R&D breakthrough, signaling that the machine would be wonderful.
Doesn't this mix present + past incorrectly?

The example you gave would be INCORRECT because it mixes present and conditional incorrectly! To correct that sentence you could do either of the following:

"The scientist is optimistic about the team's breakthrough, signaling that the machine will be (or might be) a success."
"The scientist was optimistic about the team's breakthrough, signaling that the machine would be (or could be/might be) a success."

(Note that I changed some of the wording to make it more typical of an American English style - in case you're trying to practice).

Conditional mood is confusing, and the good news is that it isn't frequently tested on the GMAT! For those who just want the quick "tell me what I need to know for the test" answer - "would" on the GMAT will be used in a sentence that combines it with a past tense verb.

Okay - but for those of you that want the longer conversation about how we use the word "would" correctly in American English - here ya go!

"Would" has three primary uses:

1. "would" for the past
2. "would" for the future from the past
3. "would" in conditional sentences

1. "would" for the past
In this scenario, you're using "would" as a sort of past tense for "will" or "going to"

The child would not sit still no matter how much his parents begged him to.
Every fall, the writer would escape to her cabin in the woods to brainstorm her next book."

2. "would" for the future [i]from the past
This is the scenario you noted above. The main action is in the past, but there is a thought about what the future *would* bring (this is the idea of the future from someone sitting in the past). The main action MUST be in the past! - you can see more about this in the All the Verbal book chapter on Verbs!

3. "would" in conditional sentences
Conditional sentences typically take on an "if - then" or "if - when" structure.

For sentences that indicate certainty (or near certainty / universal truths / etc), default to a matching simple past or present tense for everything. (Zero Conditional Sentences)
- If you buy the book, you get a rebate. (present/present)
- Your parking [i]is free when you park next door.[/i] (present/present)
- If you parked next door, you received a coupon. (past/past)

For sentences that indicate increasing levels of uncertainty (First, Second, and Third Conditional), you will start to move into more interesting verb-tense combinations. Note that I never have to formally use the IF and THEN/WHEN in every structure (I'm just including for clarity).

First Conditional (nearly certain but not guaranteed). Use the form IF (present tense), THEN (will / can / must / imperative).
- If you buy the book, then you will get to have the author sign it
- If the alarm rings, run.

Second Conditional (things that are unrealistic or very unlikely to happen). Use the form IF (past tense), THEN (would / could).
- If I won a million dollars, then I would spend a year in Costa Rica

Third Conditional (things that are unrealistic or impossible, but that happened in the past - we tend to use this for regret). Use the form IF (past PERFECT tense - had ____), THEN (would have / could have).
- I would have spent a lot more time with family, if I had known that it would be our last holiday together.

The big thing to note about EVERYTHING I've said before... If you are going to use WOULD then you almost always need it to be alongside something in the PAST!