Meaning: 'Onto' means to move to a position on a surface, which fits the action of stepping on the Moon.

Wrong options:

• into: 'Into' suggests entering a space, which does not fit the context of stepping onto a surface.
• to: 'To' indicates direction but lacks the specific connotation of movement onto a surface.
• over: 'Over' implies a position above something without direct contact, which is not suitable for the action described.

Correct answer: ta walk

Explanation: The phrase 'to walk' is the correct infinitive form that follows 'to be' in the context of expressing an action. It fits grammatically and contextually as it describes what Armstrong did on the Moon.

Meaning: 'To walk' refers to the action of moving by putting one foot in front of the other, which is what Armstrong did on the Moon.

Wrong options:

• to be walked: This passive form suggests someone else is doing the walking, which does not apply to Armstrong's action.
• walking: This gerund form does not fit the structure required after 'to be' in this context.
• that walks: This phrase is incorrect as it does not fit the infinitive structure needed here.

Correct answer: other than

Explanation: The phrase 'other than' is used to indicate exceptions, which is appropriate here as it specifies that Armstrong walked on celestial objects excluding Earth. This fits grammatically and contextually within the sentence.

Meaning: 'Other than' means apart from or excluding, which clarifies that the Moon is not Earth.

Wrong options:

• owing to: This phrase indicates a reason, which does not fit the context of comparing celestial objects.
• rather than: This phrase suggests a preference, which is not relevant to the context of walking on celestial bodies.
• as well as: This phrase indicates addition, which does not convey the intended meaning of exclusion.

Correct answer: decades

Explanation: The word 'decades' is the correct plural noun that indicates a period of ten years, which fits the context of time elapsed since the event. It aligns grammatically with the sentence structure.

Meaning: 'Decades' refers to a period of ten years, emphasizing the significant time that has passed since Armstrong's Moonwalk.

Wrong options:

• centuries: This term refers to a period of one hundred years, which is too long for the context of the event.
• seconds: This term indicates a very short time, which does not match the historical context of decades since the Moon landing.
• minutes: This term also indicates a short duration, which is not appropriate for the significant time frame being discussed.

Correct answer: in honour of

Explanation: The phrase 'in honour of' is used to express respect or recognition for someone's achievements, which is fitting in this context as it describes the naming of the lunar crater after Armstrong. This aligns with the grammatical and contextual requirements of the sentence.

Meaning: 'In honour of' means to show respect or recognition for someone or something, which is why the crater was named after Armstrong.

Wrong options:

• in terms of: This phrase indicates a perspective or consideration, which does not fit the context of recognition.
• in response to: This phrase suggests a reaction, which is not relevant to the act of naming in recognition.
• by means of: This phrase indicates a method or way, which does not apply to the context of honouring someone.