译文[误]:The weather is suddenly cold and then hot these day.

[辩误]

“忽……忽……”结构表示两个极端之间的变化和交替，形成对比或反差，相当于“一阵……一阵……”“时而……时而……” suddenly 表示一个突如其来的动作，即忽然，而不是“忽……忽……”的结构。比如：他们的关系忽好忽坏。Their relationship is now good ，now bad。还可以用one and the next表示“忽……忽……”的结构。例如：他忽而皱眉，忽而微笑。He frowned one minute and smiled the next。

译文[正]:The weather is changeable these days，now cold，now warm.

下面我们来看几个练习.

1 生意忽好忽坏.

2 他的情绪忽喜忽忧.

3 她对他忽而疼爱，忽而鄙视.

参考答案:
1 Business fluctuated from one day to the next!

2 His mood alternated between happiness and gloom.

3 She treated him with alternating affection and contempt。