Nanjing is a beautiful city. It won “China Human Habitat Environment Prize” _____ 2008.[ ]

I will stay at home and read books if it ________ heavily tomorrow.

It’s ____ to play on the road. You’d better play in a ____ place.

Let me think ____ it. The question is kind of difficult.[ ]

I found ________ difficult to work out the problem without a computer.