Meaning: 'Never' means at no time in the past or future; not ever.

Wrong options:

• Not: 'Not' is an adverb used to negate a verb, but it does not fit the structure of the sentence as it does not convey the intended meaning of unprecedented interest.
• due: 'Due' is an adjective that indicates something is owed or expected, which does not fit grammatically or contextually in this sentence.
• doubt: 'Doubt' is a noun that refers to uncertainty, which does not fit as it does not serve as an adverb to describe the frequency of learning.
• degrade: 'Degrade' is a verb that means to lower in quality or value, which is unrelated to the context of language learning and does not fit grammatically.
• develop: 'Develop' is a verb that means to grow or cause to grow, which does not fit the context of the sentence discussing people's interest in learning.
• known: 'Known' is a past participle that does not fit as it does not serve as an adverb to indicate the frequency of learning.

Correct answer: doubt

Explanation: The word 'doubt' serves as a noun that indicates uncertainty, and in this context, it is used in the phrase 'without doubt,' which is a common idiomatic expression meaning certainly or undoubtedly. This fits grammatically and contextually as it emphasizes the certainty of English being the chosen language.

Meaning: 'Doubt' refers to a feeling of uncertainty or lack of conviction.

Wrong options:

• Not: 'Not' is an adverb used for negation, which does not fit the context of expressing certainty in this sentence.
• due: 'Due' is an adjective that indicates something is owed or expected, which does not fit the context of certainty regarding language choice.
• degrade: 'Degrade' is a verb that means to lower in quality or value, which is unrelated to the context of certainty about language learning.
• develop: 'Develop' is a verb that means to grow or cause to grow, which does not fit the context of expressing certainty.
• known: 'Known' is a past participle that does not fit as it does not convey the meaning of certainty in this context.

Correct answer: known

Explanation: The word 'known' is a past participle used here as an adjective to indicate that something is recognized or acknowledged. It fits grammatically as it describes the general awareness of increased travel among people, aligning with the context of discussing the necessity of learning another language.

Meaning: 'Known' means recognized, familiar, or acknowledged.

Wrong options:

• Not: 'Not' is an adverb used for negation, which does not fit grammatically or contextually in this sentence.
• due: 'Due' is an adjective that indicates something is owed or expected, which does not fit the context of describing awareness or recognition.
• doubt: 'Doubt' is a noun that refers to uncertainty, which does not fit as it does not describe the state of being recognized or acknowledged.
• degrade: 'Degrade' is a verb that means to lower in quality or value, which is unrelated to the context of awareness about travel.
• develop: 'Develop' is a verb that means to grow or cause to grow, which does not fit the context of describing something that is recognized.

Correct answer: due

Explanation: The word 'due' is an adjective that indicates something is owed or expected, and in this context, it is used to express causation, meaning that the increased accessibility of places is a result of the development of the Internet. It fits grammatically and contextually as it explains the reason for the change.

Meaning: 'Due' means expected or owed, often used to indicate a cause or reason.

Wrong options:

• Not: 'Not' is an adverb used for negation, which does not fit grammatically or contextually in this sentence.
• doubt: 'Doubt' is a noun that refers to uncertainty, which does not fit as it does not indicate causation in this context.
• degrade: 'Degrade' is a verb that means to lower in quality or value, which is unrelated to the context of explaining accessibility due to the Internet.
• develop: 'Develop' is a verb that means to grow or cause to grow, which does not fit the context of indicating a reason for increased accessibility.
• known: 'Known' is a past participle that does not fit as it does not convey the meaning of causation in this context.