It was never clear ________ the man hadn't reported the accident sooner.(2011·江苏)
I stopped the car ____ a short break as I was feeling tired.
_________I have to give a speech, I get extremely nervous before I start.
— Oh no! We’re too late. The train _______. — That’s Ok. We’ll catch the next train to London.
Mark needs to learn Chinese _______ his company is opening a branch in Beijing.
The room is empty except for a bookshelf _____ in one corner.