脱疽未溃者，可选用下列哪种外用药：（）

A.冲和膏

B.九一丹

C.七三丹

D.金黄膏

E.白玉膏

— Would you like to come to the dinner party here on Saturday?

— Thank you. I’d love to,　　　 I’ll be out of town at the weekend

A．because

B．and

C．so

D．but