I could smoothen you could smoothen he could smoothen we could smoothen you could smoothen they could smoothen
V-ing form
I could be smoothening you could be smoothening he could be smoothening we could be smoothening you could be smoothening they could be smoothening
Perfect
I could have smoothened you could have smoothened he could have smoothened we could have smoothened you could have smoothened they could have smoothened
V-ing perfect
I could have been smoothening you could have been smoothening he could have been smoothening we could have been smoothening you could have been smoothening they could have been smoothening
Negation
Simple form
I couldn't smoothen you couldn't smoothen he couldn't smoothen we couldn't smoothen you couldn't smoothen they couldn't smoothen
V-ing form
I couldn't be smoothening you couldn't be smoothening he couldn't be smoothening we couldn't be smoothening you couldn't be smoothening they couldn't be smoothening
Perfect
I couldn't have smoothened you couldn't have smoothened he couldn't have smoothened we couldn't have smoothened you couldn't have smoothened they couldn't have smoothened
V-ing perfect
I couldn't have been smoothening you couldn't have been smoothening he couldn't have been smoothening we couldn't have been smoothening you couldn't have been smoothening they couldn't have been smoothening
Interrogative form
Simple form
could I smoothen? could you smoothen? could he smoothen? could we smoothen? could you smoothen? could they smoothen?
V-ing form
could I be smoothening? could you be smoothening? could he be smoothening? could we be smoothening? could you be smoothening? could they be smoothening?
Perfect
could I have smoothened? could you have smoothened? could he have smoothened? could we have smoothened? could you have smoothened? could they have smoothened?
V-ing perfect
could I have been smoothening? could you have been smoothening? could he have been smoothening? could we have been smoothening? could you have been smoothening? could they have been smoothening?
Interro-negative form
Simple form
couldn't I smoothen? couldn't you smoothen? couldn't he smoothen? couldn't we smoothen? couldn't you smoothen? couldn't they smoothen?
V-ing form
couldn't I be smoothening? couldn't you be smoothening? couldn't he be smoothening? couldn't we be smoothening? couldn't you be smoothening? couldn't they be smoothening?
Perfect
couldn't I have smoothened? couldn't you have smoothened? couldn't he have smoothened? couldn't we have smoothened? couldn't you have smoothened? couldn't they have smoothened?
V-ing perfect
couldn't I have been smoothening? couldn't you have been smoothening? couldn't he have been smoothening? couldn't we have been smoothening? couldn't you have been smoothening? couldn't they have been smoothening?