The word "there" is used when we're talking about the existence of something — especially in structures like: "There is / There are..." "Can there be..." "Will there be..." So in the sentence: "What types of sciences can there be in this institute?" —we're asking what types can exist in this place. "There" is needed because it's tied to the verb "be" used to express existence or possibility. Now compare that with: "What could be the best?" In this sentence, we’re not talking about what exists, but about which option is the best. So we’re identifying or choosing — not expressing existence — which means we don’t need "there." In simplest terms: Use "there" when talking about what can exist or is present. "What courses could there be?" Don't use "there" when talking about what is best, is true, or is chosen. "What could be the best option?"

Let me simplify your question to make it easier to analyze. Your sentences are, approximately, 1) "What can there be" + (adverbial clause) 2) "What can be" + (noun) Sentence 2 works with an adjective, adverb, or noun (clauses) "What can be good?" (adjective, predicate complement) "What can be in Paris?" (adverb, modifies the verb) "What can be the best?" (noun, predicate complement) Sentence 1 only works with an adverb because "there be" is not a linking verb. In order to use an adjective or a noun, you need a linking verb that links the subject of the sentence to the predicate complement. Here are some other examples with linking verbs: "What can sound good?" ("sound" is a linking verb) "Who can become a doctor?" ("become" is a linking verb)

"can/could there be" is like "can/could we have" What type of sciences can there be in this institute? This sounds fine. What type of sciences can we have in this institute? This sounds fine. What could we have the best? We could guess the meaning of this, but the poor grammar makes the meaning unclear. To improve it, we could say: What could we have that's the best? Now it sounds fine. Similarly: What could there be that's the best? Now this sounds fine too.

Great question! The difference lies in the function of there as an existential pronoun. 1. “What types of sciences can there be in this institute?” • There is used as an existential placeholder to indicate the possible existence of sciences in the institute. • The sentence is asking about the presence or availability of different sciences. 2. “What could be the best?” • Here, there isn’t needed because the sentence is about identifying the best option rather than discussing existence. • “The best” refers to a specific thing, not the existence of something in general. Short Tip: Use there when talking about the existence or presence of something (Can there be…?). If you’re focusing on identifying or defining something (What could be…?), there is unnecessary.