二次回路标号A421表示()。
A.交流电流回路A相
B.交流电压回路A相
C.直流;回路正极
D.交流回路
参考答案:A
— Excuse me, sir. The shoes are a bit small for me.
— Don't worry. I'll change them for a size. [ ]
A. smaller
B. smallest
C. larger
D. largest
左氧氟沙星为
A.B内酰胺类B.氨基糖苷类C.大环内酯类D.喹诺酮类E.四环素类