I must bubble you must bubble he must bubble we must bubble you must bubble they must bubble
V-ing form
I must be bubbling you must be bubbling he must be bubbling we must be bubbling you must be bubbling they must be bubbling
Perfect
I must have bubbled you must have bubbled he must have bubbled we must have bubbled you must have bubbled they must have bubbled
V-ing perfect
I must have been bubbling you must have been bubbling he must have been bubbling we must have been bubbling you must have been bubbling they must have been bubbling
Negation
Simple form
I must not bubble you must not bubble he must not bubble we must not bubble you must not bubble they must not bubble
V-ing form
I must not be bubbling you must not be bubbling he must not be bubbling we must not be bubbling you must not be bubbling they must not be bubbling
Perfect
I must not have bubbled you must not have bubbled he must not have bubbled we must not have bubbled you must not have bubbled they must not have bubbled
V-ing perfect
I must not have been bubbling you must not have been bubbling he must not have been bubbling we must not have been bubbling you must not have been bubbling they must not have been bubbling
Interrogative form
Simple form
must I bubble? must you bubble? must he bubble? must we bubble? must you bubble? must they bubble?
V-ing form
must I be bubbling? must you be bubbling? must he be bubbling? must we be bubbling? must you be bubbling? must they be bubbling?
Perfect
must I have bubbled? must you have bubbled? must he have bubbled? must we have bubbled? must you have bubbled? must they have bubbled?
V-ing perfect
must I have been bubbling? must you have been bubbling? must he have been bubbling? must we have been bubbling? must you have been bubbling? must they have been bubbling?
Interro-negative form
Simple form
must I not bubble? must you not bubble? must he not bubble? must we not bubble? must you not bubble? must they not bubble?
V-ing form
must I not be bubbling? must you not be bubbling? must he not be bubbling? must we not be bubbling? must you not be bubbling? must they not be bubbling?
Perfect
must I not have bubbled? must you not have bubbled? must he not have bubbled? must we not have bubbled? must you not have bubbled? must they not have bubbled?
V-ing perfect
must I not have been bubbling? must you not have been bubbling? must he not have been bubbling? must we not have been bubbling? must you not have been bubbling? must they not have been bubbling?