The time and effort he has devoted during the past few years trees in that remote area is now considered to be of great value.
A. plant
B. planting
C. to plant
D. to planting
网友回答
A. plant
B. planting
C. to plant
(答案→)D. to planting
解析：考查非谓语动词。devote … to …致力于，to为介词，故选D。