Only when he returned ________ that the war had ended and the army had come back.

A．we tell

B．we told

C．did we tell

D．were we told

某历史学习小组长为探究一专题而准备了一些材料：象形文字、楔形文字、荷马史诗、《一千零一夜》。你认为他们探究的内容是[ ]

A．东西方文明的交流

B．古代东西方的战争

C．古代的文字与文学

D．西方文明的发展