Two questions this time and many thanks for the last answers, they were very helpful. In indirect speech with regular verbs, is it correct to use gur, go or a? What are the rules for using chun, when should it be used instead of ach or go in a purpose clause? The sentence in question is from Buntus Cainte(book 2, lesson 83). "Nil moran airgid ag daoine chun toitini na tobac a cheannach, maise!"

In indirect speech with regular verbs, is it correct to use gur, go or a?

Go (or nach)+ an urú (eclipse) or n- before a vowel. is used all tenses except the past tense and it is used in the conditional mood. Nach is used for the negative.
gur (or nár) + séimhiú ( h after first letter )is used in the past tense. Nár is used for the negative.

Indirect speech is used after verbs or phrases such as the following
Deir siad , they say.
is dóca, it is probable.
Tá súil agam, I hope.
Measaim, I think, I estimate.
Ceapann sí. she thinks.
Chreid sé. he believed

Examples:
Deir siad go mbriseann sé gach rud.
They say he breaks everything.

Is dóca go gceannaíonn tú bainne.
You probably buy milk. (Literally:it is probable that you buy milk)
Measaim go ndúnann siad iad go luath. I think that they close early.
Ceapann sí nach n-osclaíonn siad an siopa go déanach san oíche. She thinks that they do not open the shop late at night.
Chreid sé nár cheart é. He believed that it wasn't right.

You don't use "a" in place of go or nach or gur or nár in indirect speech.

What are the rules for using chun, when should it be used instead of ach or go in a purpose clause? The sentence in question is from Buntus Cainte(book 2, lesson 83). "Nil moran airgid ag daoine chun toitini na tobac a cheannach, maise!"

Chun had various meanings depending on how you use it. Usually it means to, towards and if followed by a noun the noun is in the genitive case except when followed by a relative clause. This is the case in the example you gave. ....chun toitíní a cheannach...
Chun can mean in order to, as it does in the example.
Chun is normally used in a purpose clause.
úsáidtear plúr chun císte a dhéanamh. (flour is used to (in order to) make cake.
Tháinig siad ar scoil chun ceacht a fhoghlaim. They came to school to (in order to)learn a lesson.
I would say use it all the time in a purpose clause instead of ach or go.
I would use chun with "go" in phrases such as
tháinig sé chun go bhfeicfeadh sé mé, He came so that he might see me.
d'imigh sí go luath chun go mbeadh sí ann roimh an múinteoir. She went early so that she might be there before the teacher.

This is an example with ach
Tabharfaidh mé milseáin do na páistí ach iad a bheith go maith. I will give the children sweets but they have to behave.

Ach means but.
Go means that.
Life is complicated enough without using them in purpose clauses.


Go n-éirí leat ach tóg go bog é.
Kay.

Cead mille go raibh maith agat a Kay, we really appreciate getting answers. It helps our class move ahead. Thanks again. Lisa