Pine Tree Multimedia Corp. is a leading U.S. media company, focused ( ) on magazines and broadcasting.

　　A.primarily

　　B.popularly

　　C.valuably

　　D.usefully

　　【答案】A。“这家公司引领美国媒体，其主要依赖杂志和广播”。A 项 primarily：主要地;B 项 popularly：流行;C 项 valuably：有价值地;D 项 usefully：有效地。结合句意可知补充“主要地”更合适，故本题正确答案选 A。