Mary has been looking forward in the past 10 years tothe Great Wall.A. payingavisittoB. ca

问题补充：

Mary has been looking forward in the past 10 years tothe Great Wall.

A. payingavisitto

B. callon

C. beingonavisit

D. callat

答案：

(答案→)A. payingavisitto

B. callon

C. beingonavisit

D. callat

解析：句意：玛丽在过去的十年里一直盼望去长城看看。这里payavisitto+名词表示参观；callon拜访某人；beonavisit在参观中；callat sp拜访某地。这里look forward to+doing盼望做某事。故排除BD，根据句意故选A。