Flying kites, ______ some researchers point out, can not only bring about joy to us, but also promote our physical and mental health.
. The coffee is wonderful ! It doesn’t taste like anything I _________ before.
. As I am not feeling well, I really appreciate __________ to take my place.
. John, look at the time. __________ you play the piano at such a late hour ?
. Why __________ put the meat in the fridge ? It’ll stay fresh for several days.
. I wonder how he could __________ not handing in his maths exercises yesterday, for his maths teacher is always strict with his students.