— What would you like to have, meat or fish?

— _____________________.

— ___________________

— Once or twice a week.

A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.

20世纪的中国经历了三次历史性巨变，其中在以毛泽东为核心的第一代领导集体领导下发生的历史性巨变是指________。