1. Two-thirds of the apple is rotten.

2. Two-thirs of the apples are rotten.
(Both are correct,right?0

3. Most of the books were his.
4. Most of the time was spent in reading.
(Are both grammatical? Do we have to use 'in' before 'reading' in Sentence 4?)

5. The rest of the boys were nervous.
6. The rest of the milk was bad.
(Is #6 grammatical and logical?)

1. Two-thirds of the apple is rotten.

2. Two-thirs of the apples are rotten.
(Both are correct,right?0

no they ar'nt

1. Well, two-thirds of an apple being rotten is a pretty sad situation. Hopefully, the other third is still tasty!

2. Ah, it seems like the apples aren't having a great time. Two-thirds of them being rotten is quite unfortunate.

3. Yes, both sentences are grammatically correct. Most of the books were his, and most of the time was spent in reading.

4. You don't actually need to use "in" before "reading" in sentence 4. Both "most of the time spent reading" and "most of the time spent in reading" are grammatically acceptable. It's up to personal preference.

5. Oh, it seems like the rest of the boys were quite nervous. I wonder what got them so worked up!

6. Uh oh, it seems like the milk didn't have a happy ending. The rest of it being bad is definitely a disappointment. Time to go buy a new carton!

1. Both sentences 1 and 2 are correct. However, sentence 1 implies that there is one apple and two-thirds of it is rotten. Sentence 2 implies that there are multiple apples and two-thirds of all of them are rotten.

2. Both sentences 3 and 4 are grammatically correct. In sentence 4, you don't need to use "in" before "reading." The phrase "Most of the time" already implies that the time was spent in reading.

3. Sentence 5 is grammatically correct and logical. It means that the remaining boys, excluding some mentioned before, were nervous.

4. Sentence 6 is grammatically correct but logically may sound strange. It implies that there was a portion of milk, and the entirety of that portion was bad. However, in everyday communication, it's more common to say "The rest of the milk was spoiled" or "The remaining milk was bad" instead.

All the sentences are correct, yes.

In 4, you can keep "in" or omit it; either way works.

Amin