Although we met with some difficulties in building the railway, we were still about finishing it before the deadline.
A. consistent
B. enthusiastic
C. responsible
D. optimistic
网友回答
A. consistent
B. enthusiastic
C. responsible
(答案→)D. optimistic
解析：考查形容词辨析：A. consistent 一致的，B. enthusiastic 有热情的，C. responsible负责任的，D. optimistic乐观的，句意：虽然我们在建铁路时碰到了一些困难，但我们对提前完成任务还是很乐观的。选D。