paper

[itsmehihihi]

why is this sentence gramatically wrong?

Your suggestions look great on the paper,but are absolutely impractical.

[Jair dos Santos Correa]

Hello, I´m not a teacher neither a native speaker, but I think you should write the subject in the second sentence.
...but THEY are ...
OK

[bianca]

Your suggestions look great on paper, but are absolutely impracticable.

(they is implied)

[Jair dos Santos Correa]

Your suggestions look great on paper, but are absolutely impracticable.

(they is implied)

I know that dear Bianca, but I think that in this case (verb to be) it cannot be done. e.g.

"I play soccer very well, but am not so good at basketball."
"My cousin is beautiful, but is not smart"
"Our cars run very fast, but are too dirty"

Without the subject they have no sense for me
P.S. I´m just a begginer student

[bianca]

I agree that in writing you must include 'they', but in spoken E you may skip it (in this particualr sentence).

However, I agree with what you say about the other examples. Sounds odd -spoken E., probably.
I usually play it by ear.

"without...they have no sense to me."

[Anglika]

I know that dear Bianca, but I think that in this case (verb to be) it cannot be done. e.g.

"I play soccer very well, but [I] am not so good at basketball."
"My cousin is beautiful, but [she] is not smart"
"Our cars run very fast, but [they] are too dirty"

Without the subject they have no sense for me
P.S. I´m just a beginner student

They do have subjects, but as Bianca points out, they are understood - the context tells you what they are.

[itsmehihihi]

why is this sentence gramatically wrong?

Your suggestions look great on the paper,but are absolutely impractical.

I think, I above sentence is wrong because, on paper is an idiom.


Idiom: on paper

In theory, as opposed to actual performance or fact
Example: It is a good team on paper, but its members play poorly together.