Half the world's population __________ water shortages within 15 years according to the World Bank, just one of many recent alarming reports on the world's fresh water supply.
一You don’t go to that supermarket quite often, do you? —No, I only go there ______because it’s too far away from my house.
The girl arranged to have piano lessons at the training center with her sister ______ she would stay for an hour.
Dave nearly ran into a block when walking down the street with his mind ______ on the word puzzle.
______ is the kindness of the nurse that the patient can never be _______ to her.
Since nobody gave him any help, he ______ have done the research on his own.