I really appreciate____ to help me with my maths, but I’m afraid that I have no time this week.
At that time I had no idea _________ I could hand it to him without being seen.
Now there is a danger _________ the ground may fall under the heavy traffic.
We think it possible _________ the local government will be able to solve the housing problem.
She took it for granted _________ I'd be back home an hour later.
_________ caused the accident is still a complete mystery.