People living in the desert choose to keep their ancient lifestyles and customs, _______people in cities throw away their cultural traditions.

(2010·天津模拟)Get out of here at once. _________ not, I’ll phone the police.

____ you know your potential（潜力）, you have to rely on many other people to get to where you are.

________ several times，but he still doesn't know how to do it correctly.

She opened her eyes and was about to cry out ______ she heard her father urgently telling her to keep quiet.