Whenever I see the birds, I’ll flying in the sky.

Now one of the most serious problems manypeople are worried about _____ on the lack of adequate housing space.

―Why are you in such a hurry, John―There ____ a basketball match between Class 1 and our class in ten minutes.

It is so difficult a question _____ none of the kids could work it out[ ]

She was accused ____ cheating in the examand was to ____.