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