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举一反三
【单选题】When stars like our Sun die, they bloat to become red giants and then eject gigantic clouds of gas and dust into space. Increasingly, however, scientists found themselves at a profound loss to explain...
A.
explain-the possible way of death of our Sun.
B.
show the two types of red giants.
C.
discuss on the way of red giants to become white dwarfs.
D.
explore the origin of life.
【多选题】计算短路电流的目的: ( )
A.
校验保护电器 (断路器，熔断器)的分断能力
B.
校验保护装置灵敏度
C.
确定断路器的整定值
D.
校验开关电器或线路的动稳定和热稳定