The ( ) will be issued by China Import & Export Commodity Inspection Bureau or by any of its branches.

A．certification

B．certificate

C．certify

D．certificated

畸胎瘤特征性的X线征象是（）

A.肿瘤位于前纵隔

B.肿瘤呈圆形、卵圆形或分叶状

C.肿瘤内有密度减低区

D.肿瘤内有骨影或牙齿影

E.肿瘤边缘呈锯齿状或毛刺状