Scene 1

1. Remember saying simple things like I live somewhere - Dw i'n byw yn... or I work somewhere - Dw i'n gweithio yn... ?

The first part Dw i... is linked with an 'n to the verb. However, if you're using isho, you don't use an 'n' as a link.

So, Dw i isho mynd, Dw i ddim isho coffi. This is something that Welsh learners often forget. Remember: no 'n' before isho.

2. When you want someone else to do something, you use an 'i', as in Dw i isho i chi fynd i'r ysgol.
You notice the letter change here. Mynd (to go) has become fynd. Generally, any verb directly after a noun or pronoun will mutate. Look at these examples:

darllen (to read) - Dw i isho i chi ddarllen
gweithio (to work) - Dw i isho i chi weithio
cofio (to remember) - Dw i isho i chi gofio.

We can change chi to the familiar ti, e.g.
mynd i'r ysgol - Dw i isho i ti fynd i'r ysgol

Scene 3

1. Using a negative. The key word is ddim but you need to change the start of the sentence as well. So a sentence like Mae Siân isho car newydd, then changes to:
Dydy Siân ddim isho car newydd

2. There are lots of ways of saying yes in Welsh, and the trick is usually to listen out for the start of the sentence. A sentence beginning with Ydy.... will usually have Ydy as an answer, e.g.

Ydy Siân yn hoffi pasta? YDY

However, North Walians tend to answer questions that include the word "isho" with "Oes"

Ydy Siân isho panad? - OES
Ydy John isho mynd adre? - OES
The negative is NAC OES, usually pronounced Nag oes.