《闻官军收河南河北》一诗，与下列哪个历史事件有关？（）
A、泾原兵变
B、安史之乱
C、三镇复叛
D、黄巢起义
参考答案：B
The father and the son entered the tiger area _______ two doors were open at the time.
Suddenly five tigers appeared, one of which killed the father.
A．there
B．which
C．its
D．whose
电能的单位是（）。
A、千瓦
B、焦耳
C、度
D、卡／焦耳
