apple of my eye:

One's favorite person; the one you love most.

In Old English, the pupil of the eye (the round, dark center) was called the 'apple'. It was thought that the pupil was a round object much like an apple. When you look at someone, their reflection appears in your pupil. So if someone is the 'apple of your eye', he or she is someone that you look at a lot and enjoy seeing.
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1. the one you love most.
(What does 'one' refer to? A thing or a person?)

2. the pupil was a round object much like an apple.
(What is the meaning of 'much'? What other expressions can we use instead of 'much'?)

3. When you look at someone, their reflection appears in your pupil.
(Why is' their' used here? Don't we have to use his or her?)

1: A person

2: Similar in appearance to, similar to an apple
3: Their means an object belonging to a person. You could use his or her but their is more appropriate because it can be used for any gender

On question 3, his or her would be better grammar, but we probably would say their instead, as a catch-all or whomever's image is reflected.

KentG is correct on questions 1 and 2 (and mostly correct on 3).

:)

1. In the phrase "the one you love most," the word 'one' acts as a pronoun that refers to a person. It is used to represent a specific individual without mentioning their name or gender. So in the context of "apple of my eye," 'one' refers to a person who is someone's favorite or the person they love the most.

2. The word 'much' in the sentence "the pupil was a round object much like an apple" means a great deal or very similar. In this context, it signifies that the pupil was considered to be highly similar to an apple in terms of shape or appearance. Instead of 'much,' you can use expressions like 'very much like,' 'nearly like,' or 'resembling' to convey a similar meaning.

3. The pronoun 'their' is used in the sentence "When you look at someone, their reflection appears in your pupil" as a gender-neutral pronoun to refer to a singular antecedent of unspecified gender. The use of 'their' as a singular pronoun is a common way to avoid gender assumptions or to be inclusive when the gender is unknown or irrelevant. While 'his or her' is another grammatically correct option, using 'their' as a gender-neutral pronoun is becoming increasingly accepted in modern usage.