_____ earthquake measuring 9.0 struck off _____ northeast coast of Japan on March 11, 2011. [ ]

A. The; a

B. 不填; a

C. An; the

D. An; 不填

早孕时估测胎龄的最可靠指标为（）。

A.胚囊大小

B.头围

C.腹围

D.股骨长径

E.头臀长径