[Grammar] I was reading while the phone rang

[Roktim]

"I was reading while the phone rang."
"The phone rang while I was reading."

Which one is correct to use? and why?
(I thing both are correct)

 

[emsr2d2]

"I was reading [STRIKE]while[/STRIKE] when the phone rang."
"The phone rang while I was reading."

Which one is correct to use (no question mark here) and why?
(I think both are correct.)

Note my corrections above. As you can see, you need "when" in the first sentence.

Activity that was happening first + when + thing that happened second.
Thing that happened second + while + activity that was already happening.

 

[Roktim]

"I came in when he was writing."

Should I use while in this sentence?

 

[Tarheel]

"I came in when he was writing."

Should I use "while" in this sentence?

I think you can.

 

[jutfrank]

"I came in when he was writing."

Should I use while in this sentence?

Yes.