Cathy______the knowledge of radio just by staying around the radio station.(唐山市)
The doctor thought ____ would be good for you to have a holiday.
—Have you finished the book? —No. I’ve read up to _____ the children discover the secret cave.
It never occurred to me _____ you could succeed in persuading him to change his mind.
To improve the quality of our products, we asked for suggestions had used the products.
________ is of no concern to us.