In fact, the most successful way to change is not suddenly, but over a period of time.
此句出自2020版高中英语人教版,选择性必修三第二单元(P15)。竟然是中学课本,那就应该不存在不规范的问题。
我知道表示方位时间的副词如out, up, down, in, off, on, in等可以充当表语,但suddenly肯定不在其中。
这种用法是由上下文决定的,脱离上下文不行,实际上 你可以看作是一种为了简练而采取的一种省略形式, 多见于口语体。可以这样理解:In fact, the most successful way to change is not (to change) suddenly, but (to change) over a period of time. 薄冰高级语法曾提到副词作表语的用法,如:The meeting was yesterday. 你可以理解为The meeting was (held) yesterday.
 
                如果觉得我的回答对您有用,请随意打赏。你的支持将鼓励我继续创作!

In fact, the most successful way to change is not suddenly, but over a period of time.
以上的 is not 可以理解为 doesn't happen。
In fact, the most successful way to change doesn't happen suddenly, but it happens over a period of time.
 
                如果觉得我的回答对您有用,请随意打赏。你的支持将鼓励我继续创作!

 《高考英语备考1号·速效编》
						《高考英语备考1号·速效编》
					 《高考英语备考1号·写作编》
						《高考英语备考1号·写作编》
					 《高中英语晨读晚记》
						《高中英语晨读晚记》
					 《高中英语错题笔记》
						《高中英语错题笔记》
					 《零起点考大学英语》
						《零起点考大学英语》
					