[Grammar] When, while, after, or before +Ving at the beginning of a question sentence

[MichaelLu2000]

Hello guys!

As far as I know, when, while, after, and before can be used before gerund despite the fact that they are conjunctions.

Here, I would like to ask a question.

If the original sentence is like this: He cried when seeing his father, can I make a question like this based on it: When seeing whom did he cry? Or after seeing whom did he cry?

I know that before and after can be used as prepositions in a question without causing much trouble (e.g. After which war did the USA become a superpower?) and prepositions before gerunds are also common in questions (e.g. By eating what fruit can I lose more weight?), so I am wondering if after, when, before, while, can be used in the same way.

I know it might look unnatural or not idiomatic, but I just want to know if it's possible to make such a sentence.

I am asking this question because I would like to know how we make a sentence when we need to refer to a particular moment with someone.

For example,

"He said the famous line when seeing President Trump." It might be that a politician or a critic says something the moment he saw President Trump and it goes viral.

Can we turn this into a question: When seeing which president did he say the famous line? If the sentence is not possible, is there and way to express my idea?

What I come up with is "Which president did he see before he said the famous line?", "Upon seeing which president did he say the famous line?", and the most straightforward one "Seeing which president made him say the famous line?"

Any answers are welcome.

Thanks!

 

[teechar]

I'm not sure that there's a simple answer to your question. I don't find "when" natural in those sentences/contexts. However, "while" might work. It really depends on the overall sentence (especially the verb).

 

[jutfrank]

Grammatically, you can, yes.

 

[MichaelLu2000]

Grammatically, you can, yes.

So I can make a sentence like this and still follow the rules:

"When seeing whom did Jack fall in love for the first time?"

 

[MichaelLu2000]

Then is there any way to express the same idea without using this awkward structure?

 

[Rover_KE]

'Who was Jack seeing when he fell in love for the first time?'

 

[MichaelLu2000]

Maybe "Who did he meet before he fell in love for the first time?"

 

[jutfrank]

On seeing whom for the first time did Jack fall in love?

Whom did Jack fall in love with on seeing for the first time?

These sentences may be grammatical (I think!) but as we've said they don't necessarily sound good. I've used on instead of when but I think when works almost as well.

(I'm assuming that for the first time means seeing for the first time, not falling in love for the first time.)