27.If you ________ to something different, for example to a different system, task, or subject of conversation, you change to it from what you were doing or saying before.
At no time does the salesgirl get up late in the morning, for she is always too busy _____ a good rest.
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.