多形性癌细胞多为()
A.分化差的腺癌
B.分化较好的腺癌
C.分化差的鳞癌
D.分化较好的鳞癌
E.未分化癌
参考答案:D
— Listen! Helen is singing in the hall.
— It _____ be Helen. She has gone to Beijing. [ ]
A. can't
B. may
C. mustn't
D. should
选用电磁铁的功率时,电磁铁的功率应()牵引或制动功率。
A.不大于
B.不小于
C.等于
D.小于