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