Meaning: 'Existence' refers to the state of being or having reality, in this case, the reality of climate change.

Wrong options:

• existing: Existing is an adjective and does not fit as it describes something that is currently present rather than the state of being.
• exist: Exist is a verb and does not fit grammatically as it does not serve as a noun in this context.
• existed: Existed is the past tense of the verb 'exist' and does not fit as it implies a completed action rather than the ongoing state of climate change.

Correct answer: more

Explanation: The word 'more' is an adverb that appropriately modifies the adjective 'frequent,' indicating an increase in the frequency of heat waves. It fits grammatically and contextually, as it aligns with the comparative nature of the sentence discussing the rising occurrence of heat waves.

Meaning: 'More' indicates a greater degree or quantity, in this case, referring to an increase in the frequency of heat waves.

Wrong options:

• much: Much is typically used with uncountable nouns and does not fit here as it does not modify 'frequent' correctly in this context.
• lot: Lot is informal and does not function as a comparative adverb in this context, making it unsuitable.
• far: Far is used to indicate distance or extent but does not fit grammatically as a comparative for frequency.

Correct answer: keep on

Explanation: The phrase 'keep on' is a phrasal verb that indicates the continuation of an action, fitting grammatically and contextually as it describes the ongoing rise in temperatures. It aligns with the future prediction of temperature trends.

Meaning: 'Keep on' means to continue doing something, in this case, referring to the ongoing rise in temperatures.

Wrong options:

• give up: Give up means to stop trying or to quit, which contradicts the context of rising temperatures.
• put off: Put off means to delay or postpone, which does not fit the context of temperatures continuing to rise.
• go up: Go up is a simpler phrase but lacks the nuance of continuity that 'keep on' provides in this context.

Correct answer: however

Explanation: The word 'however' serves as a discourse marker that introduces a contrast or exception to the previous statement, fitting grammatically and contextually as it signals a shift in the argument regarding climatic changes.

Meaning: 'However' means 'nevertheless' or 'but,' indicating a contrast to what has been previously stated about climate change.

Wrong options:

• despite: Despite is a preposition that does not fit grammatically as it cannot introduce a clause in this context.
• whereas: Whereas is a conjunction used to compare two statements but does not fit the context of introducing a contrasting idea as effectively as 'however.'
• instead: Instead implies a substitution and does not convey the contrast needed in this context.

Correct answer: take

Explanation: The word 'take' is a verb that fits grammatically and contextually as it indicates the action of gaining or utilizing something, in this case, the advantage of adapting to climate changes. It aligns with the overall message of adaptation and benefit.

Meaning: 'Take' means to gain or seize something, here referring to the ability to benefit from changes in the environment.

Wrong options:

• see: See is a verb that means to perceive with the eyes, which does not fit the context of gaining an advantage.
• put: Put is a verb that means to place something, which does not convey the intended meaning of gaining an advantage.
• have: Have is a verb that indicates possession but does not fit as well as 'take' in the context of actively gaining an advantage.