梅毒是( )
A.STD类疾病
B.由梅毒螺旋体引起
C.分先天性和后天性
D.先天主要通过母体传染
E.后天主要通过性接触传染
参考答案:A,B,C,D,E
The architecture styles here are quite different from ________ in any city we have visited.[ ]
A. that
B. them
C. one
D. those
直流电机空载时电机的气隙磁场完全由()的电流产生。