______ lucky we are to have so many responsible teachers!

A．What

B．How

C．What a

D．How a

25岁妇女，孕36周，G1P0，合并重度子痫前期需终止妊娠，下列哪项提示胎儿已成熟

A．羊水胆红素类物质用△OD450测值＞0.02

B．卵磷脂与鞘磷脂比值(L/＞2

C．羊水肌酐测定＜2mg%

D．羊水中脂肪细胞出现率达15%

E．B型超声测胎头双顶径值8.0cm