Fill in the gaps with appropriate prepositions.

The vast number (a) _____ plant species underwater forms a beautiful ecosystem. The plants which stay underwater depend (b) _____ the light coming (c) _____ the sun (d) _____ their growth. They also draw the atmospheric carbon dioxide (e) _____ the air above and convert them (f) _____ oxygen. The flora (g) _____ the surface (h) _____ the water adds (i) _____ the aesthetic beauty. These plants sometimes span vast lengths below the surface (j) _____ the ocean.

They all rejected that idea of the Captain's.

= They all rejected the captain's idea."

In formal English, the conjunction "as" is used to introduce a clause or a phrase that indicates a comparison or the manner in which something is done. In this sentence, "as in the old days" describes how the evening was spent, implying "in the way it was done in the old days."

Conversely, "like" is primarily used as a preposition to mean "similar to" or "in the manner of," and is typically followed by a noun, pronoun, or noun phrase. While "like" is often used informally in place of "as" or "as if," it is generally considered incorrect in standard written English when introducing a clause or an adverbial phrase of comparison.

For example:

    
• Incorrect: She sings like she is a professional.
    
• Correct: She sings as if she is a professional.
    
• Correct: She sings like a professional. (Here, 'like' is a preposition followed by a noun phrase 'a professional'.)

Therefore, "as in the old days" is the grammatically correct and more formal choice for this context.

He was accused of a crime he did not commit. 

This boy is good at mathematics.

In English grammar, the verb 'call' can be used in several ways, and its usage dictates whether a preposition is required. When 'call' means 'to telephone someone', it functions as a transitive verb and directly takes an object without any preposition. For example, one would say "Please call Mr. Khan" to mean telephoning him.

Conversely, if 'call' is used to mean 'to pay a brief visit to someone', it typically forms a phrasal verb with the preposition 'on', as in "to call on someone". For instance, "We will call on our neighbours tomorrow."

Given the structure "Please call – Mr. Khan tomorrow morning", the most common and grammatically appropriate interpretation is that Mr. Khan should be telephoned. Therefore, no preposition is needed in the blank, and the sentence correctly reads "Please call Mr. Khan tomorrow morning."

The correct preposition to use when agreeing or disagreeing with a person is "with".

    
• Agree with: Used when you have the same opinion as a person.
  Example: I agree with your friend.
    
• Agree to: Used when you accept a proposal, plan, or suggestion.
  Example: She agreed to my terms.
    
• Agree on: Used when people reach a consensus about a specific matter after discussion.
  Example: We agreed on a new strategy.
    
• Agree about/upon: Used when discussing a general topic or subject.
  Example: They agreed about the importance of education.