could tread
Irregular verb: tread - trod- trod, trodden

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could tread
you could tread
she could tread
we could tread
you could tread
they could tread 	I could be treading
you could be treading
she could be treading
we could be treading
you could be treading
they could be treading	I could have trod, trodden
you could have trod, trodden
she could have trod, trodden
we could have trod, trodden
you could have trod, trodden
they could have trod, trodden	I could have been treading
you could have been treading
she could have been treading
we could have been treading
you could have been treading
they could have been treading	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't tread
you couldn't tread
she couldn't tread
we couldn't tread
you couldn't tread
they couldn't tread 	I couldn't be treading
you couldn't be treading
she couldn't be treading
we couldn't be treading
you couldn't be treading
they couldn't be treading	I couldn't have trod, trodden
you couldn't have trod, trodden
she couldn't have trod, trodden
we couldn't have trod, trodden
you couldn't have trod, trodden
they couldn't have trod, trodden	I couldn't have been treading
you couldn't have been treading
she couldn't have been treading
we couldn't have been treading
you couldn't have been treading
they couldn't have been treading	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I tread?
could you tread?
could she tread?
could we tread?
could you tread?
could they tread? 	could I be treading?
could you be treading?
could she be treading?
could we be treading?
could you be treading?
could they be treading? 	could I have trod, trodden?
could you have trod, trodden?
could she have trod, trodden?
could we have trod, trodden?
could you have trod, trodden?
could they have trod, trodden? 	could I have been treading?
could you have been treading?
could she have been treading?
could we have been treading?
could you have been treading?
could they have been treading? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I tread?
couldn't you tread?
couldn't she tread?
couldn't we tread?
couldn't you tread?
couldn't they tread? 	couldn't I be treading?
couldn't you be treading?
couldn't she be treading?
couldn't we be treading?
couldn't you be treading?
couldn't they be treading? 	couldn't I have trod, trodden?
couldn't you have trod, trodden?
couldn't she have trod, trodden?
couldn't we have trod, trodden?
couldn't you have trod, trodden?
couldn't they have trod, trodden? 	couldn't I have been treading?
couldn't you have been treading?
couldn't she have been treading?
couldn't we have been treading?
couldn't you have been treading?
couldn't they have been treading?