To solve this question, the user needs to understand prepositions and their usage. Prepositions are words that show the relationship between a noun or pronoun and other words in a sentence.

Each of the options can be used as a preposition, but the correct answer in this sentence is the option that best describes the location of the keys.

A. "At" is a preposition that indicates a specific location, but it is not the best option in this sentence. It would be more appropriate to use "at" if the sentence was "I left the keys at the office."

B. "In" is a preposition that usually describes the location of an object inside something else. For example, "The keys are in the drawer." However, it is not the best option in this sentence because the keys are not inside anything.

C. "On" is a preposition that describes a location on a surface. This option is the best choice because the keys are most likely resting on the surface of the kitchen counter.

D. "None of these" is not the correct answer as option C, "on," is the most appropriate preposition in this sentence.

The Answer is: C

To solve this question, the user needs to understand how to use prepositions of time.

The correct preposition to use when referring to a specific time of the day is "at". Therefore, the correct answer is:

The Answer is: A) at

Option B) "in" is incorrect because it is used to refer to a period of time, such as "in the morning" or "in the afternoon".

Option C) "on" is incorrect because it is used to refer to days or dates, such as "on Monday" or "on June 1st".

Option D) "none of these" is incorrect because option A is the correct answer.

To solve this question, the user needs to understand the grammar rules for subject-verb agreement and pronoun usage. In this sentence, "uncle" is the subject, and the question is asking for the appropriate pronoun to refer to him.

The correct answer is:

B. he

Explanation: In the sentence, "uncle" is a singular third-person masculine noun, and the pronoun that refers to him must also be singular and masculine. "He" is the appropriate pronoun to use in this case. Option A ("it") is incorrect because "it" is used to refer to inanimate objects or animals, not people. Option C ("you") and option D ("me") are also incorrect because they are not appropriate pronouns to refer to the uncle.