Meaning: 'On' indicates the basis or foundation of something, in this case, Chekhov's reputation being based on his plays.

Wrong options:

• and: 'And' is a conjunction that connects phrases or clauses, which does not fit the grammatical structure needed here as it does not indicate a basis.
• thus: 'Thus' is an adverb that indicates a conclusion or result, which does not fit as it does not relate to the foundation of reputation.
• out: 'Out' is a preposition that indicates movement away from something, which does not fit the context of discussing reputation.
• in: 'In' is a preposition that indicates inclusion or location, which does not convey the idea of basis in this context.
• themselves: 'Themselves' is a reflexive pronoun that does not fit as it does not relate to the subject of reputation.
• over: 'Over' is a preposition that indicates a position above or across something, which does not fit the context of discussing reputation.

Correct answer: respectively

Explanation: The word 'respectively' is used to indicate that the order of the plays corresponds to the order of the years mentioned. This fits grammatically and contextually as it clarifies the relationship between the two lists.

Meaning: 'Respectively' means in the order given, referring to the plays and their corresponding years.

Wrong options:

• and: 'And' is a conjunction that does not indicate a sequential relationship between the plays and the years.
• thus: 'Thus' is an adverb that indicates a conclusion, which does not fit the context of listing corresponding items.
• out: 'Out' does not fit grammatically or contextually as it does not relate to the order of items.
• in: 'In' is a preposition that does not convey the idea of correspondence between the plays and the years.
• on: 'On' is a preposition that does not indicate the sequential relationship needed here.
• themselves: 'Themselves' is a reflexive pronoun that does not fit the context of indicating order.
• over: 'Over' is a preposition that does not convey the necessary relationship between the plays and their respective years.

Correct answer: in

Explanation: The preposition 'in' is used to indicate the state or condition of the tone of the works. This fits grammatically as it describes the tone of the works being characterized.

Meaning: 'In' indicates a state or condition, referring to the tone of the works.

Wrong options:

• and: 'And' is a conjunction that does not fit as it does not describe the tone of the works.
• thus: 'Thus' is an adverb that indicates a conclusion, which does not fit the context of describing tone.
• out: 'Out' does not fit grammatically or contextually as it does not relate to the tone of the works.
• respectively: 'Respectively' indicates order, which does not apply to describing the tone of the works.
• themselves: 'Themselves' is a reflexive pronoun that does not fit the context of describing tone.
• over: 'Over' is a preposition that does not convey the necessary meaning related to tone.

Correct answer: out

Explanation: The word 'out' is used here to indicate the action of breaking free from a situation. This fits grammatically and contextually as it describes the characters' inability to escape their circumstances.

Meaning: 'Out' indicates movement away from a situation, in this case, breaking free from a vicious circle.

Wrong options:

• and: 'And' is a conjunction that does not fit as it does not describe the action of breaking free.
• thus: 'Thus' is an adverb that indicates a conclusion, which does not fit the context of escaping a situation.
• in: 'In' indicates inclusion, which does not fit the context of breaking free from a circle.
• respectively: 'Respectively' indicates order, which does not apply to the action of breaking free.
• themselves: 'Themselves' is a reflexive pronoun that does not fit the context of describing an action.
• over: 'Over' is a preposition that does not convey the necessary meaning related to breaking free.

Correct answer: themselves

Explanation: The word 'themselves' is a reflexive pronoun that refers back to the characters, indicating that they are the ones trapped in their circumstances. This fits grammatically and contextually as it emphasizes their personal experience.

Meaning: 'Themselves' refers to the characters in a reflexive manner, indicating their own involvement in the situation.

Wrong options:

• and: 'And' is a conjunction that does not fit as it does not refer back to the characters.
• thus: 'Thus' is an adverb that indicates a conclusion, which does not fit the context of referring to the characters.
• out: 'Out' does not fit grammatically or contextually as it does not refer to the characters.
• in: 'In' is a preposition that does not convey the necessary meaning related to the characters' involvement.
• respectively: 'Respectively' indicates order, which does not apply to referring to the characters.
• over: 'Over' is a preposition that does not convey the necessary meaning related to the characters.