I'm parsing some text from an XML file which has sentences like
"Subtract line 4 from line 1.", "Enter the amount from line 5"
i want to replace all occurrences of line with line\_
eg. Subtract line 4 from line 1 --> Subtract line\_4 from line\_1

Also, there are sentences like "Are the amounts on lines 4 and 8 the same?" and "Skip lines 9 through 12; go to line 13."
I want to process these sentences to become
"Are the amounts on line\_4 and line\_8 the same?"
and
"Skip line\_9 through line\_12; go to line\_13."