Must verb always be before 下去?
As other answers stated, 下去 can function as a directional/result word particle for 'down'  e.g. 吞下去; It can also function as a verb for 'go down' e.g. 我要下去
But when 下去 is functioning as an adverb for &quot;continue&quot;. It must be placed after a verb. e.g. 等下去

I want to say:


我吃下去 = I continue eating.

To avoid confusion, you can write &quot;我(繼續)吃下去&quot; or simply &quot;我繼續吃&quot;.
Another way to make &quot;我吃下去 (I continue eating) not ambiguous is to add more context. For example, 我再吃下去也不會喜歡上這東西