WiththesuccessfullaunchofTiangong-I,whichwas

问题详情：

With the successful launch of Tiangong-I, which was ______ breakthrough in space field, China's space dream took a step closer to ______ reality.

A. a; /                 B. the; a              C. a; the                 D the; /

【回答】

A

知识点：冠词

题型：选择题