西周实行依据____ 亲疏来确定权位和财产继承权的宗法制,并以此为原则进行____ 。
—That's true. I was too busy, so I didn't go, ______.
如图所示,两同学甩动与电流表相连的长导线,发现电流表的指针来回摆动.
(1)这种现象叫做____ 现象,这是由物理学家____ 最早发现的.
(2)产生感应电流的磁场是由____ 提供的.
You'd better ask a ______, such as your aunt or sister, to look after your children while you are away.