He made up his mind to devote his life ______ the river ______ polluted.

A．to prevent; to be

B．to prevent; from being

C．to preventing; to be

D．to preventing; from being

面部创伤清创术中。异物必须摘除的情况是（）

A.创口有急性炎症

B.异物位于大血管旁

C.深部异物

D.异物与伤情无关

E.定位不准确