阀门的公称直径是指阀门与管道连接处流通通道的名义直径，用（）表示。
A、PN
B、DN
C、N
D、P
参考答案：B
B股公司增资发行B股，比照B股首次发行审批阶段的程序办理，无须中国证监会批准发行。（）
The cellist and conductor celebrated his 80th birthday in Kremlin partly because of his fight for democracy.
