Listen to the teacher. Pause the video and try to say what you hear. The best way to improve your pronunciation is to listen and practice.

Listen to the teacher’s pronunciation (video time 6:59) of these sentences:
I’m going swimming this Saturday
Sorry, I can’t do that
These are my brothers
We’re going to those galleries on Sunday
Now record yourself and compare it to the video. Keep practising until you get it right.
Listen to the teacher’s pronunciation (video time 5:00) of these sentences:
I’m going swimming this Saturday
Sorry, I can’t do that
These are my brothers
We’re going to those galleries on Sunday