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