题目

 “大街小巷叫卖食品杂物的小贩吟叫百端，大小商店铺席连绵不断，夜市直至三更尽，五更又开晓市。”上述现象最早可能出现于 A.唐前期的长安         B.北宋开封城        C.南宋临安城      D.元朝泉州城 答案：B_______the people have become masters of their country _______ science can really serve the people. A．It is only then; thatB．It was that; whenC．It is only when; thatD．It was when; then