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