I don't like talking on ________ telephone; I prefer writing by ________ letter.[ ]

A. the; a  

B. /; a

C. /; the  

D. the; /

铅模可用于套管孔洞、破裂等漏失情况的验证，即套管侧面打印，所以也通称为套管侧面打印器。