The time and effort he has devoted during the past few years trees in that remote area is

问题补充：

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. to plant

B. to planting

C. plant

D. planting

答案：

A. to plant

(答案→)B. to planting

C. plant

D. planting

解析：句意为：他在过去的这些年里在那个偏远的地区种树所付出的时间和精力被认为是值得的。短语devote sth to sth 中to的词性是介词，故to之后应为名词或动名词形式。此处表示把时间和精力花费在了种树上，所以应为devote time and effort to planting trees.所以答案应为B。