1.   I solved the problem by adapting a red felt pen.

2.   There were several red-tipped pins protruding from it and an area of Soho had been ringed in red Marker pen.

3.   He corrects papers with a red pen.

4.   Have you got a red pen?

5.   I wonder if they get an extra allowance for red pens?

6.   Bring a red pen.

7.   Diligently Lapine would pore over the drafts, marking notes in the margins in red pen.

8.   Her boss marked up her resignation letter with a red pen, and gave it back so she could rewrite it.

9.   I tell him my red pen is gone.

10.   Mark your due date on the calendar in pencil, not red pen.