A:looked; were thinking
B:looked; had thought
C:were looking; thought
D:were looking; were thinking
△ABC中,AB=AC,点D、E、F分别在BC、AB、AC上,∠EDF=∠B.
第一次燃遍全球的战火。第一次世界大战爆发前在欧洲缔约结盟的狂潮中,组成同盟国军事集团的国家有____,组成协约国军事集团的国家有____。第一次世界大战结束后签订的条约形成了____体系.