Lots of people are wondering ________.
— Have you solved your problem? — I’ve kept on thinking about that matter__________, but I have had no idea.
— What's wrong with my son, doctor? — _________. Just a cold.
— _________ did you do with old books? — I sent them to children in poor areas.
— What______useful dictionary for beginners of English! Where did you get it? — I bought it in the bookshop.
— I visited the Purple Mountain Observatory last Sunday. —Why didn’t you tell me earlier?