颐和园由万寿山和昆明湖组成，占地面积290公顷，1998年被列入《世界遗产名录》。( )
参考答案：对
Although ______ for many years, the two old sisters recognized each other at once.
A．having been separated
B．being separated
C．having separated
D．had been separated
影响群体凝聚力的因素有( )。
A．需要的满足
B．群体目标
C．群体活动
D．领导者
