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