Microsoft has been in the leading _____ in the software industry for years.
It was _____ computer games that cost the boy a lot of time that he ought to have spent on his lessons.
_____ he’s only been learning English for a year, he speaks it very well.
--- I hear Warren _____ in a middle school. --- What? I can’t imagine him _____ as a teacher.
The 18-storeyed building, when _____, will shut out the sun _____ up the rooms in my house.
_____ and out of breath, we reached the top of the mountain and stopped _____ the beautiful scenery.