The "th" sound is the hardest sound for everybody. You need to give it special attention.
Tongue twisters with “th”
The thirty-three thieves thought that they thrilled the throne throughout Thursday.
I thought a thought. But the thought I thought Wasn’t the thought I thought I thought. If the thought I thought I thought, Had been the thought I thought, I wouldn’t have thought I thought.
Something in a thirty-acre thermal thicket of thorns and thistles thumped and thundered threatening the three-D thoughts of Matthew the thug – although, theatrically, it was only the thirteen-thousand thistles and thorns through the underneath of his thigh that the thirty-year-old thug thought of that morning.
Thirty-three thousand feathers on a thrushes throat.