One of my students wrote in her writing assignment:
1. I went to the airport with my grandfather.
2. I enjoyed looking plane at the airport.
3. I bought a plane's pen.
#2 is wrong. I corrected it to "I enjoyed watching planes at the airport."
#3 is wrong, too. My suggestion would be "I bought a plane-shaped pen."
Is 'plane-shaped' OK?
(I'm sorry to ask such a silly question.)
It's fine - if the pen was shaped lke a plane.