Some Japanese grammar doubts

Dear All

Kindly help me to understand the grammar in the followings questions;

1) れいぞこうに　ぶどう　（が）
いれてあります
In the (), why can`t I use を?

2) なつ　（なのに）, ことしは　あまり　あつくありません
In (), why can`t に　or just のに is used? Any tips on using のに、に、and なのに　which can relate to this type of sentence 2)?

Thank you for your help!

best rgds
Jason

1) れいぞうこに　ぶどう　（が） いれてあります

I might say grammatically speaking "wo" is also possible. But the meaning changes. With "ga," it means "There are grapes put in the fridge." And with "wo," it means "I have placed the grapes into the fridge." So the first one is talking about what's available in the fridge, while the second is talking about "what I've done with the grapes."


2) なつ　（なのに）, ことしは　あまり　あつくありません

Please review the explanation on "...na noni" on another thread. This whole sentence is a combination of to sentences:

なつ　です (it is summer)

ことしは　あまり　あつくありません (it is not that hot this year)

When you combine the two sentences with ".... but...." (noni), you need to turn the "desu" of the first sentence into the connective form "na" before you join them with "noni."

Whoops, I meant to say:

This whole sentence is a combination of two sentences:

Dear AK

Wow that is another perfect explanation and help given by you. Thank you once again.

I understood now.
And for the na no ni, I could understand now. I refer back to your previous explanation. I could have understood. But I just can`t believe it is right about the short sentence of `It is summer ` (なつです）.

Thanks for teaching me.
Good weekend AK!

best rgds
Jason