When the mother realized what had happened to her child, she ________ her face in her hands. So no one could see her expression.

I am _____hungry. Give me _______of milk.

There______ a number of natural mysteries in the world that even make scientists ______.

think this is the best use that we can ______ the material(材料). [ ]

ughter, job requires her to do a lot of travelling, is always away from home.