From the expression on her face we knew that the problem was .A. puzzling….puzzlingB. pu

问题补充：

From the expression on her face, we knew that the problem was .

A. puzzling….puzzling

B. puzzled…puzzled

C. puzzling..puzzled

D. puzzled..puzzling

答案：

A. puzzling….puzzling

B. puzzled…puzzled

C. puzzling..puzzled

(答案→)D. puzzled..puzzling

解析：前空意为：令人感到困惑的。后一空用puzzling说明这个问题本身上使为难的；费解的；令人困惑的。