The plane had hardly left the airport when the accident happened. -> No sooner had the plane left the airport than the accident happened.

I'm sure that someone forgot to lock the door. -> Someone must have forgotten to lock the door.

I can't believe that he passed the exam. -> I find it hard to believe that he passed the exam.

You feel tired now because you didn't sleep very well last night. -> Had you slept well last night, you wouldn't feel tired now.

The best solution was thought of by Sally. -> Sally came up with the best solution.