小灯泡接入电路中,小灯泡要能持续发光,电路必须______和______.
小灯泡要能持续发光,即灯中要有持续的电流,应在电源和电路形成通路.
故本题答案为:有电源;形成通路.
左侧多见者为
A.肾结石B.肾结核C.肾肿瘤D.肾下垂E.肾水肿
—Did your parents go to the movie yesterday evening?
— No, We ______ stayed at home watching TV.
A.both
B.all
C.either
D.none