The sentence: "Were he to leave, she could take his place" is gramatically correct.
The phrase is equivalent to "If he were to leave..." and the choice to use the inversion "Were he" instead of "If he were" is a more poetic form and adds emphasis. These types of emphasis-adding phrases are common in hypothetical situations (e.g., "Had I known" instead of "If I had known").
The choice of "were he to leave" is more controversial. It is a colloquial form of English, by which I mean that it is an informal, spoken phrase that one is unlikely to encounter in a formal, written context. One is more likely to find the phrase "If he left, she could take his place" in a formal context or the even more formal "Should he leave, she could take his place."
Could is the conditional form of the modal can. It is unclear from the context if the speaker means "would be able to take" meaning that his leaving would grant her the ability to replace him. I would tend to think not, rather that she has the ability to replace him already, independent of his choice to leave, and that if he left it is possible that she would replace him.
Could you please provide the options or context for me to be able to determine which one is grammatically correct?
Technically, you could use retrospect as a verb, but it is not good usage. It would be better to say "I remember."
The correct sentence would be "He could not have been there". This is because 'can' is in the present tense and doesn't agree with the rest of the sentence.
If you were to quote correctly the sentence we could venture an answer.
No, it is not. The "question word," why, should be at the beginning of the sentence. Why was she promoted?
This sentence is grammatically correct.
Could you please provide the options or context for me to be able to determine which one is grammatically correct?
The correct sentence would be "He could not have been there". This is because 'can' is in the present tense and doesn't agree with the rest of the sentence.
Technically, you could use retrospect as a verb, but it is not good usage. It would be better to say "I remember."
Depending on the sentence, not unless could be the correct form.
The verb in the given sentence, "could be" is in a conditional present tense.
Him and I have a report to do.
rule that could explain what makes a sentence grammatically correct or not before the noun."
If you were to quote correctly the sentence we could venture an answer.
No, it is not. The "question word," why, should be at the beginning of the sentence. Why was she promoted?
By adding the appropriate subject-auxiliary inversion, the sentence could be rewritten as an interrogative sentence.
No, the sentence is not correct. It should be "The boy could blow out the candle." The verb "blow" needs to be in the base form after "could."