注意：否定句可用另外两种句式表示。（北京安通学校提供）

　　1）Not until…在句首，主句用倒装。例如：

　　Not until the early years of the 19th century did man know what heat is. 直到19 世纪初，人类才知道热为何物。

　　Not until I began to work did I realize how much time I had wasted. 直到工作，才认识到我已蹉跎了几多岁月。

　　2）It is not until… that… 。例如：

　　It was not until I began to work that I realized how much time I had wasted.

　　19.10 表示"一…就…"的结构

　　hardly/scarcely…when/before, no sooner…than　和as soon as都可以表示"一…就…"的意思。例如：

　　I had hardly / scarcely got home when it began to rain. 刚回家，就下起雨来了。

　　I had no sooner got home than it began to rain.

　　As soon as I got home, it began to rain.

　　注意：如果hardly, scarcely 或no sooner置于句首，句子必须用倒装结构。例如：

　　Hardly / Scarcely had I got home when it began to rain.

　　No sooner had I got home than it began to rain.