Is there such a thing as [i-adj]でした ?

[pacerier]

I have learnt that the past tense of 広いです is 広かったです.

But I was thinking, isn't 広いでした also the past tense of 広いです ?

So am I right to say that there are 2 grammatical past tense forms of 広いです,

and both of them are acceptable and commonly used ?

 

[Toritoribe]

No. 広いでした is wrong. You can't use it.

 

[pacerier]

Btw is there a grammatical explanation why 広いでした is wrong ?

 

[Glenn]

広い carries all the meaning and function of "to be wide", whereas です is just there to show politeness (it doesn't have any other grammatical function). The past of 広い is 広かった, and the past of 広いです is 広かったです.