could oscillate
Regular verb: oscillate - oscillated- oscillated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could oscillate
you could oscillate
she could oscillate
we could oscillate
you could oscillate
they could oscillate 	I could be oscillating
you could be oscillating
she could be oscillating
we could be oscillating
you could be oscillating
they could be oscillating	I could have oscillated
you could have oscillated
she could have oscillated
we could have oscillated
you could have oscillated
they could have oscillated	I could have been oscillating
you could have been oscillating
she could have been oscillating
we could have been oscillating
you could have been oscillating
they could have been oscillating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't oscillate
you couldn't oscillate
she couldn't oscillate
we couldn't oscillate
you couldn't oscillate
they couldn't oscillate 	I couldn't be oscillating
you couldn't be oscillating
she couldn't be oscillating
we couldn't be oscillating
you couldn't be oscillating
they couldn't be oscillating	I couldn't have oscillated
you couldn't have oscillated
she couldn't have oscillated
we couldn't have oscillated
you couldn't have oscillated
they couldn't have oscillated	I couldn't have been oscillating
you couldn't have been oscillating
she couldn't have been oscillating
we couldn't have been oscillating
you couldn't have been oscillating
they couldn't have been oscillating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I oscillate?
could you oscillate?
could she oscillate?
could we oscillate?
could you oscillate?
could they oscillate? 	could I be oscillating?
could you be oscillating?
could she be oscillating?
could we be oscillating?
could you be oscillating?
could they be oscillating? 	could I have oscillated?
could you have oscillated?
could she have oscillated?
could we have oscillated?
could you have oscillated?
could they have oscillated? 	could I have been oscillating?
could you have been oscillating?
could she have been oscillating?
could we have been oscillating?
could you have been oscillating?
could they have been oscillating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I oscillate?
couldn't you oscillate?
couldn't she oscillate?
couldn't we oscillate?
couldn't you oscillate?
couldn't they oscillate? 	couldn't I be oscillating?
couldn't you be oscillating?
couldn't she be oscillating?
couldn't we be oscillating?
couldn't you be oscillating?
couldn't they be oscillating? 	couldn't I have oscillated?
couldn't you have oscillated?
couldn't she have oscillated?
couldn't we have oscillated?
couldn't you have oscillated?
couldn't they have oscillated? 	couldn't I have been oscillating?
couldn't you have been oscillating?
couldn't she have been oscillating?
couldn't we have been oscillating?
couldn't you have been oscillating?
couldn't they have been oscillating?