Do you think _________ possible for so many people to sit in such a small room?

Only after he had spent several nights working on the math problem _______ to wonder whether the problem was wrongly set.

Not only ________learn a foreign language, but also ______ master it well.

  ________ to an Australian home, you will probably eat outside and cook meat on the open fire.

 Don't just give me a simple “yes” or “no” to my questions. Explain _______ possible.