I think you've forgotten to post the word in parentheses.
I am going to try to help you, anyway.
Here are my guests. :)
1. Heís only had it for two week.
He only have stay tow weeks ago.
2. One of his friends sold it to him
A friend has sold it to him
3. It wasnít very expensive.
It didnít COST too much
4. I asked him if I could have a ride on it.
I said 'could I have a ride on it'?
5. Itís essential to wear a helmet when you ride it
You have to wear a helmet when you ride it
6. Sunbathing isnít as much fun as skiing.
Skiing is more fun than to ski.
7. I was taught to ski by my mother
My mother taught me to ski.
8. She advises me to do some exercises first.
She said,í you'd better do some exercises first.'
9. my father doesnít ski now, but he did when he was young.
My father used to ski when he was young.
10. he says he doesnít have enough time to come with us.
He says heís too busy to come with us.