--With the country’s pension fund gap being wider than ever, retirement age should be postponed immediately.
---Easier said than done. we take all factors into account, we shall be faced with some other social problems.
A. Unless
B. Until
C. When
D. Once
网友回答
(答案→)A. Unless
B. Until
C. When
D. Once
解析：句意：--随着国家养老基金缺口越来越大，退休年龄应该立刻被推迟。--说起来容易做起来难。--如果我们不将所有的因素考虑在内，我们会面临很多其他的社会问题的。用unless引导条件状语从句，“除非，如果不”，until“直到”，when“当…时候”，once“一旦”，根据句意选A。