Low-carbon lifestyle is of great benefit to improve the world environment, but the problem is difficult to ．
A. solve
B. be solved
C. solve with
D. solving
网友回答
(答案→)A. solve
B. be solved
C. solve with
D. solving
解析：考查固定句型：sb/sth is+adj+to do“某人/某物做…是如何的“，这个句型是主动表被动，句意是：低碳生活方式对提高世界环境很有益，但这个问题很难解决。选A。