Sandy went to Tibet by train this summer for the first time. She had an unusual .A. experi

问题补充：

Sandy went to Tibet by train this summer for the first time. She had an unusual .

A. experience

B. experiment

C. knowledge

D. condition

答案：

(答案→)A. experience

B. experiment

C. knowledge

D. condition

解析：experience经验，经历；experiment实验，尝试；knowledge 知识，学问；condition条件，环境。句意：这个暑假桑迪第一次乘火车去了西藏。她有一段不寻常的经历。结合语境可知选A。