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