【题目】Scientists and experts said it was a big ________in China's space history that Chang'e-II has been smoothly sent around the moon.
A. leap
B．chance
C．time
D．opportunity
在线课程【答案】A
【解析】考查名词辨析。句意为：科学家和专家说嫦娥Ⅱ号的成功绕月飞行是中国航天史上的一大飞跃。leap名词，意为“飞跃”；chance/opportunity“机会”；time“时间”。