Conjugating modality

Besides what's covered in my previous verb conjugation post, verbs can also be conjugated for some modalities. This is done with prefixes.

To Need - Ru Fahei
	Positive	Negative
Basic	Ifahei	Ufahei
Do	Kifahei	Kufahei
Will	Sifahei	Sufahei
Would	Zifahei	Zufahei
Can	Lifahei	Lufahei
Could	Pifahei	Pufahei
May/might	Mifahei	Mufahei
Must	Nifahei	Nufahei
Ought to/should	Xifahei	Xufahei

The basic positive and negative forms are mostly used for answer yes/no questions. The most correct way to answer a question is to repeat the verb with i- or u-.

Example:
O amufu gaparu nei?
     Will you eat the apple?
Ihamufu/Uhamufu
     Yes/No (in the future)
Ihamu/Uhamu
     Yes/No (now)
I/U
     Yes/No (impolite, implies annoyance or frustration with the question)

The other modalities are used similarly to their English equivalents. For example will gets the prefix si-, and will not gets the prefix su-.

Just the prefixes:

Modality	Positive	Negative
Basic	I-	U-
Do	Ki-	Ku-
Will	Si-	Su-
Would	Zi-	Zu-
Can	Li-	Lu-
Could	Pi-	Pu-
May/might	Mi-	Mu-
Must	Ni-	Nu-
Ought to/should	Xi-	Xu-