comfortable

[Freeguy]

A. I was very comfortable speaking to everyone.
B. I was very comfortable to speak to everyone.

Why don't we use B? Don't we use adjectives + to ? If so, why not using infinitive in front of "comfortable" ?

 

[emsr2d2]

A. I was very comfortable speaking to everyone.
B. I was very comfortable to speak to everyone.

Why don't we use B? Don't we use adjectives + to ? If so, why not using infinitive in front of "comfortable" ?

No, we don't. The construction is "to be comfortable doing something".

I don't know how you think we could use the infinitive in front of comfortable. Can you write the sentence you are suggesting?

 

[Freeguy]

The same az B, for example. You said it's wrong! I got it.

What are the other expressions ( or adjectives ) that follow gerund and not infinitive?

 

[5jj]

Why don't we use B? Don't we use adjectives + to ?

We do - I was very happy to speak to every one.

If so, why [STRIKE]not using[/STRIKE] don't we us the/an infinitive in front of "comfortable" ?

We have to learn how each adjective is used.

I was pleased to see her.
I was intent on seeing her
It was nice seeing/to see her.
etc.

 

[MikeNewYork]

The same az B, for example. You said it's wrong! I got it.

What are the other expressions ( or adjectives ) that follow gerund and not infinitive?

In my opinion, "speaking" is not a gerund in your sentence. It is a present participle, used as a modifier. A gerund is used as a noun and there is no place for a noun in that construction.