"The book was not good"

Translation: Kitabu hakikuwa kizuri

[Xerxes661]

it is "haki-", as opposed to "haku-" because of the ki- in the noun kitabu ?
What is the general rule?

[BBazzle]

Why hakikuwa? Why not just kitabu si kizuri?

[ChelseaCSc]

I think kitabu si kizuri would be 'the book is not good', as opposed to 'was not'