He appears to be optimistic, but, , he is quite pessimistic.
A. in particular
B. on one hand
C. for one thing
D. as a matter of fact
网友回答
A. in particular
B. on one hand
C. for one thing
(答案→)D. as a matter of fact
解析：考查短语辨析。in particular 特别地，on one hand 一方面，for one thing 首先，as a matter of fact 事实上，句意：他似乎很乐观，但是事实上他非常地悲观。所以选D。