问题补充：
He is an old doctor with a lot of . But he has never travelled by air before.Taking a plane was quite experience for him this time.
A. experience; an
B. experiences; an
C. experience; /
D. experiences; /
答案：
(答案→)A. experience; an
B. experiences; an
C. experience; /
D. experiences; /
解析：考查experience用法。Experience有两层意思，第一种指经历，是一个可数名词；第二种是指经验，是不可数名词。句意：他是一个经验丰富的医生，但是他以前从来没有做过飞机，这次对他来说坐飞机是一次不同寻常的经历。第一空是不可数名词经验，第二空是可数名词经历。故A正确。
