Māori Grammar

Nā... can be used to give the reason for something happening. When used with i... ai it refers to the past:

nāku - I was the reason
nāu - you were the reason
nāna - he.she was the reason

nā tāua - you and I were the reason
nā māua - the two of us (not you) were the reason
nā kōrua  -  you two were the reason
nā rāua  -  those two (they two) were the reason

nā tātou  -  all of us (including you) were the reason
nā mātou  -  all of us (not you) were the reason
nā koutou  -  you all were the reason
nā rātou  -  they (all of them) were the reason

nā Rangi - Rangi was the reason
nā Rangi rāua ko Mere - Rangi and Mere were the reason
nā te kaiako - the teacher was the reason
nā ngā tamariki -  the children were the reason

Following the subject of the sentence is the object (without i). In the past, i and ai preceed and follow the verb:

Nāku te māmā  i harikoa ai.
I was the reason the mother was happy.

Nā te kaiako ngā tauira i hoha ai.
The teacher was the reason that the students were bored.

Nā koutou ahau i pōhara ai.
You were the reason that I was broke.

Nā Mere a Hemi i oho ai.
Mere was the reason Hemi woke up.

Note the difference between past, present and future:

Nā te ua ngā tamariki i māku ai.
The rain was the reason the children got wet.

Nā te ua ngā tamariki e māku nei.
The rain is the reason the children are getting wet.

Mā te ua ngā tamariki e māku ai.
The rain is the reason the children will get wet.