— Is Ms Smart a nice teacher?
— Yes, . [ ]
A. she is
B. he is
C. she isn't
D. he isn't
答案:A
满水的主要危害是降低蒸汽质量,损害甚至破坏蒸汽过热器。
一个精馏塔,其塔底热源提供1000J的热,进料带来200J的热,采出带走500J的热。并且此塔底热源给另一塔提供200J的热。则此塔再沸需要()J的热。
A.400
B.500
C.700
D.800