---He failed his exam again. ---But what did you _____ ? Had he ever been working hard?
Please give me a call ______ you arrive in New York.
I don't mind her criticizing me, but ______ is how she does it that I object to.
As a global financial center, Hong Kong serves as the ______ role in the course of Renminbi internationalization.
There is a ______ going on in America public schools over the best way to teach English to foreign students.
—Can I go out to play, Mom? —You can ______ you stay in the garden.