• A) in - This is correct because "in the garden" indicates that Mary is inside or within the garden.

• B) at - This is not correct in this context. "At the garden" is not typically used to describe someone being inside a garden. "At" is often used for locations in a broader sense, not indicating someone is physically inside an area.

• C) on - This is incorrect. "On" would imply being on top of something, like "on the table" or "on the floor," which doesn't make sense for a garden.

• D) into - This is also incorrect in this context. "Into" suggests movement towards the inside of something, but the sentence implies Mary is already in the garden, not moving into it.

• B) are you - This is correct because "Sarah, what are you doing?" is the proper way to ask someone what they are currently doing.

• A) she is - This is incorrect because it doesn’t match the structure needed for the question.

• C) are - This is incorrect because it does not include the subject "you," which is needed for the question.

• D) is - This is incorrect as it is missing the subject "you" and does not fit the question format.

The reasons:

• B) are listening to - This is correct because "listening to" is the proper phrase used to describe the action of hearing something, like the radio. The verb "are" agrees with the plural subject "John and Mary."

• A) are listening on - This is incorrect because "listening on" is not a correct preposition for this context.

• C) is listening on - This is incorrect because "is" does not agree with the plural subject "John and Mary."

• D) is listening to - This is incorrect because "is" does not agree with the plural subject "John and Mary."

• D) is - This is correct because the question is about what John is currently doing. The verb "is" agrees with the singular subject "John" and is used in the present continuous tense.

• A) are - This is incorrect because "are" is used with plural subjects, not with the singular subject "John."

• B) are - This is incorrect for the same reason as above; it should be "is" for a singular subject.

• C) does - This is incorrect because "does" is used for forming questions about habitual actions or general truths, not for asking about ongoing actions.

The reasons:

• B) The sun is in the sky. - This is correct because "the sun" is a specific object, so "the" is used, and "the sky" is a specific, singular location.

• A) The sun is in a sky. - Incorrect because "a sky" is not specific; "the sky" is the appropriate term.

• C) Sun is in a sky. - Incorrect because it lacks the article "the" before "Sun" and "a sky" is not specific.

• D) A sun is in a sky. - Incorrect because "a sun" is not used when referring to the specific sun in our solar system.