单项选择题
A. NATO B. Russia C. the United States D. the United Nations
A. one’s emotions can influence one’s facial expressions B. the frown-free people will never feel sad or angry C. one’s facial expressions can influence one’s emotions D. people can control emotions by frowning more often
A. Greenspan’s remarks. B. the slack US business. C. the excessive optimism. D. the weakened US economy.