雅尔塔体系的实质是： [ ]
A．两种社会制度的斗争
B．美苏争霸斗争
C．美苏对世界势力范围的划分
D．雅尔塔会议精神的贯彻
答案：C
What _____ you do on your last school trip? [ ]
A. do
B. did
C. were
