Please check for my mistakes in these sentence builing and help me with the remaining sentence, thank you very much!

1, We couldn't have managed without my father's money.
If it hadn't had my father's money, I couln't have managed.

2, I had only just put the phone down when the boss rang back.
Hardly had I put the phone down when the boss rang back.

3, It was Walter Raleigh who introduced potatoes and tobacco into England.
The English owe potatoes and tobacco to Walter Raleigh.

4, We may not be able to give the concert.
The concert may have to be cancelled.

5, The only thing that prevented the passing of the bill was the death of the Prime Minister.
Had it not been for the death of Prime Minister the bill wouldn't have been passed

6, She wore a hearing aid, even though she couln't hear the phone ring perfectly well.
She wasn't so ...................................

7, The Yeti has very rarely been seen at this altitude.
There have been few sightings of The Yeti at this altitude.

8, " If my members agree to that I'll be very surprised," said the union delegate.
The union delegrate observed that if his members agreed to that, he would be very surprised.

9, I'm sorry I missed Professor Baker's lecture.
I'm sorry not .............................................

10, I was not surprised to hear that Harry had failed his driving test.
It came .........................................................