Correct the mistakes in these sentences. Use the full forms of the verbs. Use punctuation marks at the end of the sentences:

1. How long has your grandparents been driving this car?

How long have your grandparents been driving this car?

2. How long has they been looking for a house?

How long have they been looking for a house?

3. Tony has not ben reading this book.

Tony has not been reading this book.