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刷刷题刷刷变学霸
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.
【单选题】“超声波在污水处理中的应用研究”的最佳检索表达式为?
A.
超声波and污水and应用研究
B.
超声波and污水
C.
超声波and(污水or废水)and应用研究
D.
超声波and(污水or废水)