The government ______ air quality in urban areas from levels one to five: excellent, fairly good, slightly polluted, poor and dangerous.
Before going abroad he devoted all he could _______ his oral English.
He spent every minute he could _____ spoken English.
He ran as fast as he could _____ to catch the early bus.
Everyone in our class was working hard and doing what we could _______ a good college.
The wild flowers looked like a soft orange blanket _____ the desert.