Do you happen to know who's working on the implementation plan?

- who's working on the sales forecast
Do you happen to know who's working on the sales forecast?

- why they haven't paid yet
Do you happen to know why they haven't paid yet?

- why they haven't signed the agreement yet
Do you happen to know why they haven't signed the agreement yet?

- Do you have any idea
Do you have any idea why they haven't signed the agreement yet?

- why he's so frustrated
Do you have any idea why he's so frustrated?

- how they will react
Do you have any idea how they will react?

- I have no idea
I have no idea how they will react.

- 過去形で
I had no idea how they would react.

- if that would work
I had no idea if that would work.

- what course of action to take
I had no idea what course of action to take.

- 現在形で
I have no idea what course of action to take.

- why they are not keeping everyone on the same page
I have no idea why they are not keeping everyone on the same page.

I don't understand why they are not keeping everyone on the same page.

- why he hasn't given you a status update yet
I don't understand why he hasn't given you a status update yet.

- why he's in a bad mood lately
I don't understand why he's in a bad mood lately.

- why he has been working overtime for weeks
I don't understand why he has been working overtime for weeks.

- I'm not sure
I'm not sure why he has been working overtime for weeks.

- when to expect him back
I'm not sure when to expect him back.

- if I understand your question
I'm not sure if I understand your question.

- if I can finish this report by tomorrow
I'm not sure if I can finish this report by tomorrow.

- if I can help you with this file
I'm not sure if I can help you with this file.

- I don't know
I don't know if I can help you with this file.

- if I can come back by 4:00
I don't know if I can come back by 4:00.

- who's working on the implementation plan
I don't know who's working on the implementation plan.