The thing is that I know what kind of problem I face with the sentences you will read below but I don’t know the definition of problem. It is like: I drink a liquid stuff but later I learn that it is called water. So I thought that the most adequate definition could be ‘how to solve two passive voices confusion in one sentence’. Including the sentences below, if you have any idea how to define grammatical problems in English for those who are not native English speaker, please share.

Sentences:

“What kind of things will happen when metallic elements started to be used smoothly in 3D printers.”

“What kind of things will happen when metallic elements are started to be used smoothly in 3D printers.”

“What kind of things will happen when metallic elements are started to use smoothly in 3D printers.”

I am aware that there is going to be, at least, one passive voice in the aforementioned sentences certainly. My idea is: “…elements are started” is correct but for the rest I am quite confused?

The thing is that I know what kind of problem I face with the sentences you will read below but I don’t know the definition of problem. It is like: I drink a liquid stuff but later I learn that it is called water. So I thought that the most adequate definition could be ‘how to solve two passive voices confusion in one sentence’. Including the sentences below, if you have any idea how to define grammatical problems in English for those who are not native English speaker, please share.

Sentences:

“What kind of things will happen when metallic elements start to be used smoothly in 3D printers.”

“What kind of things will happen when metallic elements are started to be used smoothly in 3D printers.”

“What kind of things will happen when metallic elements are started to use smoothly in 3D printers.”

I am aware that there is going to be, at least, one passive voice in the aforementioned sentences certainly. My idea is: “…elements are started” is correct but for the rest I am quite confused?