He kept yawning in class this morning. That is _____ he stayed up late doing his homework last night.
I have already made a decision what attitude to adopt _________ this matter.
The millionaire passed away, leaving his children with a large _________.
I’m sure David _________ when we get home.
— Did you know any Chinese before you arrived in Beijing?— Never ________ it, actually.
What surprised me most was _________ to meet his girlfriend again.